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Chapter 1: Running the Game

Running Downtime

Source GM Core pg. 44
There's more to life than fighting monsters and looting treasure. What happens when a PC wins a deed to a tavern in a game of cards, crafts a magical item, builds a home, or pursues a relationship? All these goals and more are resolved by running downtime. Downtime is the space between adventures, where your PCs take a step back before the next chapter starts. In downtime, you can sum up the important events of a whole day with just one roll. Use this mode when the characters return home or otherwise aren't adventuring.

Usually, downtime is a few minutes at the start of a session or a break between major chapters of an adventure. On rare occasions, you might have a whole session of downtime to play out a specific story. As with exploration, you might punctuate downtime with roleplaying or encounters when it's natural to do so.

Stakes: None to low. Downtime is the counterpart to adventuring and covers low-risk activities.

Time Scale: Downtime can last days, weeks, months, or years in the game world in just a few minutes of real time at your game table.

Actions and Reactions: If you need to use actions and reactions, switch to exploration or encounter mode. A creature that can't act is unable to perform most downtime activities, but it can take long-term rest.

Depth of Downtime

Source GM Core pg. 44
Determine how involved your group wants downtime to be at the start of the game. If your players vary greatly in preference, you might need to find a middle ground, or some way to give the players least interested in downtime something they would find compelling. You can adjust downtime depth as the game goes along, and you might find it becomes more important to the players as their connection to the setting grows stronger.

Pay attention to the amount of real-world time you spend in downtime and the level of detail. Downtime should rarely last a whole session. Usually, a half hour between significant adventures is about right, and 15 minutes for shorter lulls in the action, such as when PCs return to a town briefly in the middle of an adventure. You can extend this time as needed for more detailed roleplaying scenes.

For the level of detail, it's important to give more than just an overview, but often the basics will do. “A fleet of merchant ships arrives in the port, and an officer puts you to work unloading cargo” might do for using Sailing Lore to Earn Income, and “Your shipment of iron arrives late, but you're able to complete the armor” could be enough for Crafting. Go deeper if the player sets out to do something specific or asks questions you think have potential for an interesting story, but be careful with too much detail, as you run the risk of boring most of the table with minutiae.

Group Engagement

Source GM Core pg. 45
One major challenge of downtime is keeping the whole group involved. When you can, combine multiple people's tasks into one. For instance, if one PC wants to Earn Income with Performance and another wants to offer their services as a medic, you might say that a traveling caravan is stopping briefly, seeking entertainment and treatment for diseases and injuries their group suffered on the road. That means you can put both PCs in the same scene. You can also look for downtime activities that affect multiple characters' interests. For instance, if the rogue's contact at the thieves' guild wants a special magical cloak, a different PC might Craft that cloak. This lets those PCs help each other more directly. If the barbarian's player doesn't plan to do anything in downtime, you might let the barbarian Aid another character in crafting weapons—feeding the forge and working the bellows, for instance.

If a player really isn't interested in downtime, they might not want to engage at all. In that case, it's best to shorten the time you spend on downtime and give their actions a one-sentence description. If other players want a deeper downtime experience, consider extending game sessions or running side sessions for just those players.

Campaigns without Downtime

Source GM Core pg. 45
There are two ways you might end up with a game that has no downtime: no time and no interest. In the first, the story moves along so quickly that the PCs don't really have time to engage with downtime. Think of it like a breakneck action movie, where the characters barely have time to breathe before they're on to the next challenge, and even the end of an adventure is a cliffhanger.

In the second, you and the other players just don't care about downtime at all. It doesn't interest you. In this case, just summarize what happens between adventures and skip using any downtime rules.

If you skip downtime, you might not need to adjust your game. The money PCs can earn during downtime is minor compared to what they can gain through adventures. However, the PCs will have less choice in what items they get if they don't Craft or earn extra money to buy items.

Long-Term Goals

Source GM Core pg. 45
Downtime is more satisfying when the PCs work toward long-term goals rather than perform disconnected tasks. You can ask players what their PCs' goals are, and also look for storylines they're interested in that you can use as seeds for long-term goals. Long-term goals might include running a business, creating a guild, establishing an arcane academy, returning a despoiled land to its natural splendor, reforming local politics, or rebuilding a ruin. Goals involving organizations are a good opportunity to use the leadership subsystem on page 204. If players don't have clear ideas for their goals, look at their backgrounds, NPCs they know, and things they've expressed interest in during adventures to develop some suggestions. Remember that you're not trying to get them to accept your exact suggestions but to pick a goal they really like.

Long-term goals should shape the game, and reinforcing their progress is key. Show changes, good and bad, that result from the PCs' efforts, both in downtime and on their adventures if applicable. This doesn't have to be subtle! You can directly say, “You've been trying to get the magistrate to allow you to buy this plot of land, but the fact that you entered the wizard's tower illegally seems to have soured him toward you.”

Think ahead in stages. For instance, if a PC wants to run a business, you might have them...
  • Start with a simple stand to sell their wares.
  • Show they're drawing big crowds and need to expand.
  • Build a storefront.
  • Open to modest success.
  • Get a small but loyal following.
  • Hire employees to keep up with demand.
  • Deal with supply issues or competition.
  • Get enough interest in a nearby settlement that they might want to expand their business.
And so on. You can deliver each of these details through a little vignette. For example, if you use the second bullet point, you might describe the throng of people crowded around the PCs' stand and say they sold out of goods before half the people were served. Downtime goals are a great way to weave the PCs' agency into the story.

Success and Failure

Source GM Core pg. 46
Success at a reasonable long-term goal should be likely, but not guaranteed. Give the player an expectation of how likely their goal is to work out based on how ambitious it is. Be clear about how much downtime it will take compared to the amount of downtime you expect the party will get during your campaign. Then, let the player decide how to commit their downtime and to which tasks.

Repeated failures or outside problems could lead to the whole goal failing. It happens! But give the player a fair chance. Even if their goal is really hard to achieve—like driving the undead out of Ustalav—they might find a way. Don't undermine their efforts or ideas, but do make clear the magnitude of the task they've chosen. Remember that even if a goal fails, the effort was worthwhile, and the PCs might still achieve smaller successes along the way that open up new goals. For instance, the PCs might not succeed at driving the undead out of Ustalav, but in the process, they might discover part of a powerful holy spell that might be able to, if it can somehow be reassembled.

A failure or a success at a long-term goal can be a major emotional beat for the character. They've changed the world, after all! Don't shortchange it just because it happened in downtime. In fact, because it might have taken place over multiple sessions, the player might have been looking forward to the results for a really long time!

Playing out a Downtime Day

Source GM Core pg. 46
At the start of a given day of downtime, have all the players declare what their characters are trying to accomplish that day. You can then resolve one character's efforts at a time (or group some characters together, if they're cooperating on a single project). Some activities, such as Earning Income, require only a simple roll and some embellishment from you and the player. Other activities are more involved, incorporating encounters or exploration. You can call on the players to play out their downtime activities in any order, though it's often best to do the simplest ones first. Players who aren't part of a more involved activity might have time to take a break from the table while the more complex activities are played out.

Characters can undertake their daily preparations if they want, just as they would on a day of exploration. Ask players to establish a standard set of preparations, and you can assume the characters go through the same routine every day unless their players say otherwise.

Cooperation

Source GM Core pg. 46
Multiple characters can cooperate on the same downtime task. If it’s a simple task that requires just one check, such as a party Subsisting as they await rescue on a desert island, one character rolls the necessary check while everyone else Aids that character. If it’s a complex task, assume all of them are working on different parts of it at one time, so all their efforts count toward its completion. For example, a party might collaborate to build a theater, with one character drawing up architectural plans, one doing manual labor, and one talking to local politicians and guilds.

Checks

Source GM Core pg. 46
Some downtime activities require rolls, typically skill checks. Because these rolls represent the culmination of a series of tasks over a long period, players can’t use most abilities or spells that manipulate die rolls, such as activating a magic item to gain a bonus or casting a fortune spell to roll twice. Constant benefits still apply, though, so someone might invest a magic item that gives them a bonus without requiring activation. You might make specific exceptions to this rule. If something could apply constantly, or so often that it might as well be constant, it’s more likely to be used for downtime checks; for instance, Assurance could apply.

Longer Periods of Downtime

Source GM Core pg. 46
Running downtime during a long time off—like several weeks, months, or even years—can be more challenging. However, it’s also an opportunity for the characters to progress toward long-term plans rather than worrying about day-to-day activities. Because so much time is involved, characters don’t roll a check for each day. Instead, they deal with a few special events, average out the rest of the downtime, and expend any resources, such as their general cost of living.

Events

Source GM Core pg. 46
After the characters state what they want to achieve in their downtime, select a few standout events for each of them—usually one event for a period of a week or a month, or four events for a year or longer. These events should be tailored to each character and their goals, and they can serve as hooks for adventures or plot development. A character using Perform to Earn Income could produce a commanding performance of a new play for visiting nobility (who end up so impressed that they give the party their next quest). Someone using Crafting might get a lucrative commission to craft a special item (that must be recovered from a renowned master thief in the next session). A character with Lore might have to research a difficult problem (uncovering signs of an impending cataclysm that will need the PCs to act in order to avert it).

PCs who want to do things that don't correspond to a specific downtime activity should still experience downtime events; you just choose the relevant skill and DC. For example, if a character intends to build their own library to house their books on magic, you might decide setting the foundation and organizing the library once construction is finished are major events. The first could be a Crafting check, and the second an Arcana or Library Lore check.

Average Progress

Source GM Core pg. 47
For long periods of downtime, you might not want to roll for every week, or even every month. Instead, set the level for one task using the lowest level the character can reliably find in the place where they spend their downtime (see Difficulty Classes on page 52 for more on setting task levels). If the character fails this check, you might allow them to try again after a week (or a month, if you're dealing with years of downtime). Don't allow them to roll again if they succeeded but want to try for a critical success, unless they do something in the story of the game that you think makes it reasonable to allow a new roll.

The events you include during a long stretch of downtime should typically feature higher-level tasks than the baseline. For instance, a character Earning Income with Sailing Lore for 4 months might work at a port doing 1st-level tasks most of the time, but have 1 week of 3rd-level tasks to account for busy periods. You'll normally have the player roll once for the time they spent at 1st-level tasks and once for the week of 3rd-level tasks.

Tasks and Events

Source GM Core pg. 47
Players will often look to you for tasks they might take on during downtime, especially if they’re looking to Earn Income. You should also interject special events to surprise your players and add interesting scenes. If you need some quick ideas for tasks characters might offer a PC, look at the tables below for inspiration. The Earn Income tasks are arranged with tasks appropriate for low-level PCs first, but most can be adapted to the level you need. For the events, you might need to “zoom in” to focus on a special scene or even a short encounter or adventure.

Table 1-1: Earn Income Events

Academia, Library, Other Educational Lore
Work at a school or library
Compile information on a distant land for an expedition
Serve as administrator for a school or library
Acquire a rare book on dragons for a local noble
Crafting
Make tools for local farmers
Brew a crate of healing potions for a local church or hospital
Sew a dress for a noble’s debutante ball
Supply magical weapons for the palace guard corps
Engineering Lore
Assess the fortifications built to protect a town
Plan the mechanism for a drawbridge
Create schematics for a new mill
Food or Drink Lore
Brew simple ale or cook an ordinary dish for the local inn
Identify a dozen bottles of wine
Create a showpiece dish for an upcoming festival
Create a nine-course meal for a noble banquet
Genealogy Lore
Compile a family tree for a minor noble family
Determine next of kin to settle an inheritance dispute
Map the web of intermarriages of a sprawling royal family
Determine the lineages of an ancient civilization
Trace the lost heir of an ancient empire
Guild Lore
Recruit initiates for a guild
Identify symbols of an ancient guild in a tome
Consult on rearranging a guild’s hierarchy
Oversee the merger of two guilds or one guild splitting into two
Herbalism Lore
Supply poultices to a physician
Prepare herbs for a small restaurant
Identify the poisonous plant eaten by a local lord
Legal Lore
Clear some minor red tape
Defend someone charged with theft
Bring a corrupt noble to justice through the legal system
Find loopholes in a contract made with a devil
Mercantile Lore
Price a crate of imported textiles
Find the best trade route for a pirate crew to raid
Set exchange rates for a trade consortium
Mining Lore
Work a shift in a coal mine
Determine where a raw ingot was mined
Prospect to find a site for a new mine
Performance
Busk for townsfolk at a street fair
Play in the orchestra at an opera
Attend a society figure’s salon
Perform for visiting nobles
Impress a visiting maestro to bring glory to your hometown
Put on a performance for a patron from another plane
Politics Lore
Lobby for a vote or decision to go a certain way
Smear a noble to lower their station
Sailing Lore
Crew a ship on a short voyage
Render a ship in dry-dock seaworthy
Pilot a ship through monster-infested waters
Underworld Lore
Find out where a stolen item ended up
Get someone an audience with the head of a thieves’ guild
Smuggle a shipment of valuables out of the city
Warfare Lore
Teach a spear fighting class at a dojo
Instruct an officer in various military stratagems
Advise a general in planning a battlefield offensive

Table 1-1: Earn Income Events

Academia, Library, Other Educational Lore
Work at a school or library
Compile information on a distant land for an expedition
Serve as administrator for a school or library
Acquire a rare book on dragons for a local noble
Crafting
Make tools for local farmers
Brew a crate of healing potions for a local church or hospital
Sew a dress for a noble’s debutante ball
Supply magical weapons for the palace guard corps
Engineering Lore
Assess the fortifications built to protect a town
Plan the mechanism for a drawbridge
Create schematics for a new mill
Food or Drink Lore
Brew simple ale or cook an ordinary dish for the local inn
Identify a dozen bottles of wine
Create a showpiece dish for an upcoming festival
Create a nine-course meal for a noble banquet
Genealogy Lore
Compile a family tree for a minor noble family
Determine next of kin to settle an inheritance dispute
Map the web of intermarriages of a sprawling royal family
Determine the lineages of an ancient civilization
Trace the lost heir of an ancient empire
Guild Lore
Recruit initiates for a guild
Identify symbols of an ancient guild in a tome
Consult on rearranging a guild’s hierarchy
Oversee the merger of two guilds or one guild splitting into two
Herbalism Lore
Supply poultices to a physician
Prepare herbs for a small restaurant
Identify the poisonous plant eaten by a local lord
Legal Lore
Clear some minor red tape
Defend someone charged with theft
Bring a corrupt noble to justice through the legal system
Find loopholes in a contract made with a devil
Mercantile Lore
Price a crate of imported textiles
Find the best trade route for a pirate crew to raid
Set exchange rates for a trade consortium
Mining Lore
Work a shift in a coal mine
Determine where a raw ingot was mined
Prospect to find a site for a new mine
Performance
Busk for townsfolk at a street fair
Play in the orchestra at an opera
Attend a society figure’s salon
Perform for visiting nobles
Impress a visiting maestro to bring glory to your hometown
Put on a performance for a patron from another plane
Politics Lore
Lobby for a vote or decision to go a certain way
Smear a noble to lower their station
Sailing Lore
Crew a ship on a short voyage
Render a ship in dry-dock seaworthy
Pilot a ship through monster-infested waters
Underworld Lore
Find out where a stolen item ended up
Get someone an audience with the head of a thieves’ guild
Smuggle a shipment of valuables out of the city
Warfare Lore
Teach a spear fighting class at a dojo
Instruct an officer in various military stratagems
Advise a general in planning a battlefield offensive

Buying and Selling Items

Source GM Core pg. 48
After an adventure yields a windfall, the characters might have a number of items they want to sell. Likewise, when they're flush with currency, they might want to stock up on gear. It usually takes 1 day of downtime to sell off a few goods or shop around to buy a couple items. It can take longer to sell off a large number of goods, expensive items, or items that aren't in high demand.

An item can usually be purchased at its full Price and sold for half its Price. Supply and demand can affect these numbers, but only occasionally. However, the game leaves it up to you to determine what items the PCs can and can't purchase and the final market Price for them. Settlements the size of a town or bigger typically have at least one vendor for basic, common gear, and even magic and alchemical items of 1st level. Beyond that, it all depends on how much you want to allow the players to determine their abilities and how much verisimilitude you want in your game. You can set the specifics where you need, but let's look at three possibilities.

PCs can buy what they want where they want. You gloss over the details of markets. PCs can sell whatever they want for half the Price and buy any item to which they have access at full Price. This approach is focused on expediency over verisimilitude and is likely to reduce the number of unusual or distinctive items the PCs have, as many players seek out the ones that most directly support their characters' strengths. This still means there's a limit on purchasing uncommon or rarer items, but you could even do away with rarity if your group wants, or add a surcharge instead (depending on your group's play style, that could be anywhere from 10% to 100% for uncommon items, and 25% to 500% if you also want to open up all rare items).

PCs can buy what they want but must put in additional effort. If they want to sell or buy items, PCs must be in a location where the markets can support that. They can usually sell a single item for half its Price, but the Price for something already plentiful on the market could drop lower, typically to 25% or 10%, or be refused entirely if there's a glut. Buying an item usually costs the full Price; buying higher-level items (or uncommon items if they're available at all) requires seeking out a special vendor or NPC and can take extra time, representing a real investment by the PCs. They might be unable to find the item at all even after their time investment, based on the settlement's parameters. This approach allows PCs to determine some of their items, but it forces them to really work to get more powerful items and discourages looting every enemy to sell off fairly ordinary armor. This can be the most work for you but can make the world feel diverse and complex.

Magical markets are rare or nonexistent. PCs get what they find in adventures and can Craft their own items, if you allow them to get formulas in some way. If you have magical marketplaces at all, their selections are small. They sell items at full Price and have difficulty attaining the funds to buy more items. They might purchase items for half of the Price but are far more selective about what they take. If you use this approach, PCs are far more likely to use strange items they find but might be dissatisfied or even underpowered depending on what items you give them. Even in this style of game, you might want to allow them to get weapons and armor with fundamental runes fairly easily or make sure you award those on a regular basis.

Money in Downtime

Source GM Core pg. 49
While the amount of money the PCs can earn during short periods of downtime is significantly less than the value of the loot they gain while adventuring, it can still serve as a satisfying bonus. The PCs might use their money to outfit themselves better, donate it toward a good cause, or pool it together to save for a major purchase. If you find that a PC tends to forget about their money or save it up more cautiously than they really need to, offer them rewarding opportunities to spend it. For instance, they might be approached to contribute to a charity in desperate need or sponsor an artist looking for a patron.

Investments

Source GM Core pg. 49
The downtime system isn't meant to deal with investing money, receiving interest, or the like just to make more money. Rather, investing should result in changes in the world. PCs might invest in founding a museum and find on their return that the collection has grown. If they fund an expedition, they might get access to interesting trade goods later on.

When characters are investing in a major endeavor, the amount of in-world time invested often matters more than the money. While spending additional money greatly increases the efficiency of Crafting an item, you can't build a fort in a day just because you have enough money to pay for the whole process. Downtime is a good opportunity for characters to start long processes that can continue in the background as the PCs adventure, provided they can find a trustworthy, competent person to run things in their stead.

Money during Long Periods of Downtime

Source GM Core pg. 50
If the PCs have a very long time between adventures, especially years, they have the opportunity to collect a great deal of money through downtime. Use the guidelines for average progress (page 247) and cost of living on page 295 of Player Core to figure out how much they get. Because you’re trying to convey that a long time has passed, have them spend it before you jump to the end of downtime. What did they invest in during those years? What drew their interest? Did their fortunes rise or fall? Did they acquire interesting objects or hire compelling people? Consider this expenditure another way to show how the PCs impact the world.

Cost of Living

Source GM Core pg. 50
Tracking cost of living is usually best reserved for months or years of downtime since that's when someone might earn a substantial amount of money from downtime activities and find that costs really add up. You can usually ignore it if there are only a few days of downtime, though if a PC is roleplaying a fine or extravagant lifestyle, you might charge them during even short periods of downtime to reinforce the story they're telling. For short periods of downtime, characters are usually just passing through a settlement or spending a bit of time there. They can use the prices for inn stays and meals found on page 294 of Player Core. For long stretches of downtime, use the values on the Cost of Living table, repeated below for convenience. Deduct these costs from a character's funds after they gain any money from their other downtime activities.

A character can live off the land instead, but each day they do, they typically use the Subsist activity (Player Core 232) to the exclusion of any other downtime activity.

Table 6-16: Cost of Living

Standard of LivingWeekMonthYear
Subsistence*4 sp2 gp24 gp
Comfortable1 gp4 gp52 gp
Fine30 gp130 gp1,600 gp
Extravagant100 gp430 gp5,200 gp
* You can attempt to Subsist using Society or Survival for free.

Long-Term Rest

Source GM Core pg. 50
Each full 24-hour period a character spends resting during downtime allows them to recover double what they would for an 8-hour rest. They must spend this time resting in a comfortable and secure location, typically in bed.

If they spend significantly longer in bed rest—usually from a few days to a week of downtime—they recover from all damage and most nonpermanent conditions. Characters affected by diseases, long-lasting poisons, or similar afflictions might need to continue attempting saves during downtime. Some curses, permanent injuries, and other situations that require magic or special care to remove don't end automatically during long-term rest.

Retraining

Source GM Core pg. 50
The retraining rules on page 440 of the Player Core allow a player to change some character choices, but they rely on you, as the GM, to decide whether the retraining requires a teacher, how long it takes, if it has any associated costs, and if the ability can be retrained at all. It's reasonable for a character to retrain most choices, and you should allow them. Only choices that are truly intrinsic to the character, like a sorcerer's bloodline, should be off limits without extraordinary circumstances. Consider what effort each PC puts forth as they retrain, so you can describe how they feel their abilities change. What kind of research and practice do they do? If they have a teacher, what advice does that teacher give?

You can run a campaign without retraining if you want the PCs to be more bound by their decisions or are running a game without downtime. However, if your campaign doesn't use downtime rules but a player really regrets a decision made while building or leveling up their character, you might make an exception for them, either by letting them simply change the decision or by finding a rare in-story element to justify the decision, such as a rare potion or a magical nexus that alters time.

Try to make retraining into a story. Use NPCs the character already knows as teachers, have a character undertake intense research in a mysterious old library, or ground the retraining in the game's narrative by making it the consequence of something that happened to the character in a previous session.

Time

Source GM Core pg. 50
Retraining a feat or skill increase typically takes a week. Class features that require a choice can also be retrained but take longer: at least a month, possibly more. Retraining might take even longer if it would be especially physically demanding or require travel, lengthy experimentation, or in-depth research, but usually, you won't want to require more than a month for a feat or skill, or 4 months for a class feature.

A character might need to retrain several options at once. For instance, retraining a skill increase might mean they have skill feats they can no longer use, and so they'll need to retrain those as well. You can add all this retraining time together, then reduce the total a bit to represent the cohesive nature of the retraining.

Instruction and Costs

Source GM Core pg. 50
The rules abstract the process of learning new things as you level up—you're learning on the job—but retraining suggests that the character works with a teacher or undergoes specific practice to retrain. If you want, you can entirely ignore this aspect of retraining, but it does give an opportunity to introduce (or reintroduce) NPCs and further the game's story. You can even have one player character mentor another, particularly when it comes to retraining skills.

You don't have to use teachers, but it gives you a great way to introduce a new NPC or bring back an existing one in a new role. The role of a teacher could also be filled by communing with nature for a druid, poring through a massive grimoire for a wizard, and so on. The important part is the guidance gained from that source. The following list includes sample teachers.
  • Archwizard Koda Mohanz, wizard academy proctor
  • Bagra Redforge, aged artisan
  • Baroness Ivestia II, tutor in etiquette and social maneuvering
  • Byren Effestos, Esquire, advisor in matters of law, politics, and finance
  • Dr. Phinella Albor, professor of medicine and surgery
  • Dr. Revis Enzerrad, mystic versed in the occult
  • Grita the Swamp Sage, purveyor of strange draughts and cryptic riddles
  • Jeballewn Leastfire, expert and tutor in alchemical experimentation
  • Kpunde Neverlost, retired veteran adventurer
  • Lyra, teller of legends and master of handicrafts
  • Major Venaeus, instructor of military tactics
  • Mother Elizia, high priest and religious scholar
  • Professor Kurid Yamarrupan, senior university lector
  • Quintari Solvar, coach for fitness and healthy living
  • Ragged Sanden, hermit and speaker for nature
  • Silent Flame, Master of the Seventeen Forms
  • Tembly the Daring, veteran acrobat and circus performer
  • Twelve Fingers, experienced thief and spy
  • Wen Hardfoot, well-traveled scout and naturalist
  • Zuleri Gan, conductor, playwright, and music scholar
Any costs to retraining should be pretty minor—about as much as a PC could gain by Earning Income over the same period of time. The costs are mostly there to make the training feel appropriate within the context of the story, not to consume significant amounts of the character's earnings. A teacher might volunteer to work without pay as a reward for something the character has already done or simply ask for a favor in return.

Extreme Retraining

Source GM Core pg. 51
By the default rules, PCs can't retrain their class, ancestry, background, attribute modifiers, or anything else intrinsic to their character. However, you might be able to find a way to make this happen in the story, going beyond the realm of retraining and into deeper, story-based quests. Class and attribute modifiers are the simplest of these changes to justify, as they could come about solely through intense retraining. Especially at low levels, you might let a player rebuild their character as a different class, perhaps starting by retraining into a multiclass dedication for their new class and swapping into more feats from that dedication as partial progress toward the class change. Just be mindful that they aren't swapping over to switch out a class they think is great at low levels for one they think is stronger at high levels. Retraining a class or ability modifiers should take a long time, typically months or years.

Changing an ancestry or heritage requires some kind of magic, such as reincarnation into a new form. This might take a complex ritual, exposure to bizarre and rare magic, or the intervention of a deity. For instance, you might require an elf who wants to be a halfling to first become trained in Halfling Lore, worship the halfling pantheon, and eventually do a great service for halflings to get a divine blessing of transformation.

Retraining a background requires altering the game's story so that the events the PC thought happened didn't. That can be pretty tricky to justify! One easy scenario is that they had their memory altered and need to get it magically restored to reveal their “true” background—the new retrained background.

Of course, in all these cases you could make an exception and just let the player make the change without explanation. This effectively acknowledges that you're playing a game and don't need an in-world justification to make certain retroactive changes. For some groups, it might be easier, or require less suspension of disbelief, to ask the group to adjust their ideas of what previously happened in the game—retconning events—than to create an in-world justification for something like an elf turning into a halfling via magic.