Mastering character cards
About 15 minutes · No jargon · Works on any site
Everything that matters about writing a character the AI can actually play, on one page. Read it once, then leave it open in the other tab while you write.
The whole guide, in one line
A card is not a description of a person. It is a small engine the AI runs every turn.
Contents
The one idea
The AI is a text predictor. It reads your card and continues it. A list of adjectives gives it nothing to continue, so it falls back on the most average version of that archetype, and you are bored by message twenty.
What it can continue is cause and effect. Why they are like this, what they want, what is in the way, how they feel about it. Compare:
[Personality: Bubbly, Shy, Loyal] [Likes: Music, Coffee] [Backstory: Had a hard childhood]
{{char}} forces a bubbly front around people because being actually known scares her; she learned early that the loud, easy version of herself got left alone, and the quiet one got questions. The act slips when she is tired, which is most nights after close.
The second version hands the AI a cause, a tension, a front and what is behind it, and a reason the behaviour changes over time. That is the guide in one paragraph. The rest is how to get there quickly.
How the AI reads it
Five things worth knowing before you write a word. Everything else in this guide follows from them.
It follows patterns, not rules
Your card is not a spec the AI obeys. It is evidence of what kind of story this is, and the AI writes more of that. Telling it what not to do mostly just puts the thing you banned into its head.
Left alone it writes the average
A vague card drifts to the median version of that archetype within a few messages. Your one line about a character who resists is competing with ten thousand stories where she does not.
Names are heavy
"A night-shift pharmacist in Leeds" is five words that carry weather, wages, accents and institutions for free. "The distant East" carries nothing. Use real places wherever you can.
It skims the middle
A 3,000-word card is not three times the depth of a 1,000-word one. It is a big middle to half-read. Put what must never drift at the top and the bottom, and keep the middle short.
Say each fact once
If her eye colour lives in the card, a lorebook entry and two greetings, one day you change one of them and she starts flipping between the two. Say it once. Reinforce it by referring back to it, not by repeating it.
The first one has a sharp consequence worth pulling out on its own: a sample of the voice beats any description of it. The AI imitates what it sees far more faithfully than it follows what it is told. If a character keeps coming out wrong, write them coming out right before you reach for another adjective.
{{char}} speaks in a dry, sarcastic way.
{{user}}: Rough night? {{char}}: "Define rough. I've still got both kidneys, so by this place's standards I'm thriving."
This cuts both ways. A greeting written in purple prose teaches the AI to write purple prose back. Your card is the strongest style instruction in the whole conversation, so write it in the register you want returned.
Three questions that make a person
Before appearance, before a name if you like, answer these three in a sentence each. Most of a character falls out of them.
What do they want?
And what is in the way? Money, to be left alone, a person, to disappear, to be seen. Best if the obstacle is not the user, so the story does not end when you show up.
Wants off nights. Days mean the promotion. The promotion means being seen.
What shaped them?
Everything they did not choose. Where they grew up, what their parents did, the one event that bent the line. Three angles are worth checking separately here.
Parents were nurses. Steered her into pharmacy, "medicine without the blood".
What do they like, and why?
The why is the whole thing. "Likes music" is nothing. A taste with a reason attached is a person, and it tells the AI how they behave when the subject comes up.
Plays five-a-side on Thursdays, badly and loudly. Hates LinkedIn.
Those three angles, because writers tend to do one and forget the others. Body: age, build, one physical fact and what it taught them. World: class, job, home, the town. Head: ambitions, temper, the thing they are ashamed of.
And on the third question, notice how much work a reason does. "She will listen to anything with a loud guitar, with one exception: the jam band album that played on loop in the kitchen where she washed dishes at sixteen, which she will leave a bar over." That is a like, a dislike, a job she used to have and a mood, in one sentence.
One last question to ask yourself: where will they be after the user stops talking to them? If the honest answer is "nowhere, they only exist for the user", the card will feel hollow.
Friction, and details it can pull on
Roleplay runs on friction. A character who wants one thing and is stopped by another has something to do in every scene. A character with no obstacle has one interesting conversation and then repeats it.
So give them two or three contradictions: a front and what is under it, a want that fights another want, a loyalty that costs them something. Give them a flaw that actually costs, and a pleasure that lets them have fun. Perfect people are boring to talk to.
Then, for the big moments, write a detail rather than a summary. Small, specific, sensory, and left unfinished. The AI cannot do much with a diagnosis. It can do a great deal with an image:
{{char}}'s mother died in a house fire when she was nine. She barely escaped. It was very traumatic and she still has nightmares.
The last thing {{char}} remembers of the flat is the smell of burnt toast and her mother's keys still hanging in the inside of the door.
The same applies to subtext. If you spell out what the behaviour means, the AI will narrate the meaning every single time. Put the cause and the behaviour near each other and let the reader join them up:
{{char}} is bubbly and outgoing, but it is a mask. She hides deep childhood trauma behind her smile and is secretly very lonely.
Day to day, {{char}} is the loudest person in any room and the first to suggest another round. She spent most of her childhood in a house where nobody talked at dinner.
Leave gaps on purpose. Every detail you pin down is a constraint, and every gap gets filled by the AI's average. Both are useful. Pin down what changes behaviour and leave the rest. Ask of each sentence: does this change what they do, or how they feel? If not, cut it.
From blank page to draft
The fastest way in is to start with one concrete image and ask the next question each fact suggests. You are not filling in a form, you are following a life and noticing where it bends. Follow the bumps, not the straight line. If the first answer is the obvious one, take the second.
Someone's actual notes
Who am I thinking of?
A man. Call him Marek Nowak. Broad, not tall. A nose that was broken once and set badly. Say 44.
So he was born around 1982. Where?
Łódź, Poland. Parents moved to Bradford when he was nine, right after the wall came down.
What shaped a Polish kid in Bradford in the nineties?
Getting called things at school. The Premier League on a neighbour's telly. A dad who had been an engineer and was now driving a van. Marek is good with his hands because that was the one place his dad still had authority.
So he loves football. Take the second answer.
He hates it. Boxing gym at fourteen instead, because it was cheap and nobody asked where you were from. That is the nose.
So where did that go?
Never turned pro. At nineteen he broke his right hand on a lad's head outside a chip shop. Six months suspended. He took it as a sign and did a plumbing apprenticeship.
Where is he now?
Two-van plumbing firm in Leeds. Divorced at 38 because he was never home and never said why. Trains kids at the gym Tuesdays and Thursdays.
What does he want?
For his son Kacper to call. He would never say so. What he says he wants is a third van.
Seven questions and Marek has a body, a country, a class, a reason he is good with his hands, a criminal record, a divorce, a kid who will not call, and a want he would never admit to. The last line is the whole lesson: what he says he wants is not what he wants.
Two things that do a lot of work for free. Pick a real place, because a named town brings weather, wages and accents with it. And pick an age, because an age pins an era: what was on the radio when they were fifteen, what their parents did, what the town was like then.
Writing the Definition
The Definition is the main field of the card, the part the AI sees every single turn. Write it in plain sentences that mostly start with the character's name, and make each one carry a because, a so, or a but.
There is no single right structure, but this order keeps the important things near the edges, where the AI pays most attention, and it reads like a life rather than a form:
- 01
Who they are now
Name, age, what they do, where. One or two sentences. This is the anchor.
- 02
Body
Build, face, the one or two physical facts that are causes rather than decoration.
- 03
Where they came from
Childhood in a few sentences, and what it did to them.
- 04
The bump
The defining event or choice, written as a moment rather than a summary.
- 05
How they move through the world
Work, money, habits, tastes with reasons, what they enjoy, what they cannot stand.
- 06
People
One line per relationship that matters, named. Include the one who is gone.
- 07
Voice
How they talk, ideally with one short line of them talking.
- 08
Present state
Where their head is right now, and what is still unresolved.
Prose, bullet points and tagged sections all work. What matters is that you write real sentences inside whichever you pick. "Likes: coffee, rain" is lumber in any format.
Definition length, in tokens (roughly 4 characters each)
Around 900 to 1,500 tokens is the sweet spot for one character. Fantasy or sci-fi that needs scaffolding can justify going toward 2,000. Past that, the middle gets skimmed and the character drifts. The creator shows you this count as you type.
Two things to keep out. First, secrets need a condition: who would they tell, and what has to happen first? A secret with no lock on it gets confessed to a stranger on message two. Second, do not cast the user. Every line that fixes who the user is ("your childhood friend", "your bodyguard") is a line that makes every chat start the same way.
Worth knowing: the Definition, the greeting and the lorebook go to the AI. The tagline, public description, tags and content warnings do not, so write those for people browsing.
A card, taken apart
About 260 tokens. Not a template to fill in, just every move above in one place.
Dana Okafor is a 34-year-old night-shift hospital pharmacist in Leeds. Her parents, Nigerian-born nurses, steered her into pharmacy because it was "medicine without the blood", and she took the night shift eight years ago because it paid more and kept her away from the day staff who keep asking when she will apply for the lead role she has never wanted. Dana runs the dispensary like a cockpit, every drawer labelled in her own block capitals, because the one error she made as a trainee (a decimal point, caught by a nurse, never reported) still wakes her at four in the morning. She is quick, dry and generous with juniors, and she lies to her mother every Sunday about "seeing someone". She plays five-a-side on Thursdays, badly and loudly, hates LinkedIn with a passion she cannot fully explain, and keeps a 1998 Walkman in her locker because her brother Tobi gave it to her before he moved to Lagos and slowly stopped calling. She wants out of nights, but days mean the lead role, and the lead role means being seen.
Nigerian-born nurses … "medicine without the blood"
Her job has a cause. The AI can now talk about her parents and her ambivalence without being told how.
the lead role she has never wanted
A want with an obstacle, and it is never resolved. The question is live on turn one and on turn three hundred.
a decimal point, caught by a nurse, never reported
Small, specific, unfinished. It explains the labelled drawers and gives her something to hide or confess.
lies to her mother every Sunday
A mask and a truth, with a schedule attached. A Sunday scene writes itself.
five-a-side, badly and loudly … hates LinkedIn
One joy, one petty dislike. Imperfect people are far more playable than competent ones.
The greeting
If the Definition is the skateboard, the greeting is the ramp. It sets the tone, the place, the time of day, what the character is doing, and one slice of who they are. The best first greetings are neutral meetings: the user walks into their life the way a stranger would.
Then add alternate greetings, each showing a different side. Six that reliably work:
3:12 a.m. The dispensary hatch is half shuttered, and the only sounds on the corridor are the fridge alarm that nobody has fixed since March and a tinny Walkman leaking drum and bass from under the counter. {{char}} slides the shutter up the rest of the way without looking at you, one hand already reaching for the clipboard. "If this is the Ward 9 Oramorph again, I need the prescriber's signature this time. Not a text. A signature." She finally looks up, clocks that you are not who she expected, and the clipboard lowers an inch. "Oh. You're new. Right. Who sent you down here at this hour?"
Notice what it does: time and place in the first line, the character mid-task, a problem already moving, a call-back to the card, and a direct question that hands the turn over. You could be a nurse, a porter or somebody who should not be there, and the scene still works. That is the test. Give the user more than one thing to grab, and make them a participant rather than a spectator watching someone be impressive.
Heard it before
The air felt heavier somehow.
His presence filled the room.
The forest held its breath.
Nobody has ever beaten me.
Atmosphere lines that mean nothing, and characters announcing their own legend. The AI learns to write them back at you. Also skip writing the user's thoughts and feelings for them.
Greeting length, in tokens
Do you need a lorebook?
Probably not, and that is the honest first answer. A lorebook holds extra text that only gets sent to the AI when a keyword shows up in the recent chat. It is for things the AI does not already know and the character would not carry around in their head: a made-up technology, a cult, a side character who appears in some chats. If your character lives in Leeds, the AI already knows Leeds.
Definition
Always on
Constants. True on turn one and turn three hundred.
Greeting
Right now
States. Where they are and what they are doing today.
Lorebook
Only when mentioned
Detail that should surface when a scene touches it.
Constants in the Definition, textures in the lorebook. Anything that must be true every turn belongs in the Definition, because there are no always-on lorebook entries.
Keywords are the interface. Pick words a scene would naturally use, not one generic word that fires constantly:
The Roundhay Road gym
A members' boxing club above a shuttered carpet shop on Roundhay Road, Leeds, open since 1989. Subs are twelve pounds a month, waived quietly for kids who cannot pay. Run by Bev, sixty-three, who took it over from her late husband. The ring-3 ropes sag on the red side and everyone knows not to lean on them.
If you are inventing a world, give it enough that it can put pressure on the character: name the country and the street, decide the technology level once, and give money a scale. A 5,000-coin bounty means nothing until you know what a loaf costs.
When it goes wrong
Most cards fail in the same handful of ways. If you can name the symptom, the fix is usually short.
“They are flat. They just answer questions.”
Why
Nothing in the card pushes against anything else. Traits with no causes, a want with no obstacle, no dislikes.
Fix
Add two tensions and three dislikes with reasons. Write one small unfinished memory.
“Every chat goes straight to bed.”
Why
The card spends hundreds of words on kinks. It is the strongest style instruction in the whole context and the AI is imitating it.
Fix
Cut it to a line or two about how they found out and when it is earned. Put the weight on a life.
“They confess everything in two messages.”
Why
A secret with no lock on it. The AI has the secret in front of it and every reason to be forthcoming.
Fix
Attach a condition to each secret: who they would tell, and what has to happen first.
“Great at first, repetitive by message thirty.”
Why
One thread. The AI solved the character, has nothing left to resolve, and starts looping.
Fix
Give them several things going on at once: work, money, someone who left, a hobby, a grudge.
“I am just watching them be impressive.”
Why
Ranks, titles and abilities with no cost, plus a greeting where they perform and you observe.
Fix
Drop the rank system. Give every ability a cost. Let them lose. End the greeting with a question.
“They do not sound like themselves.”
Why
The voice is described with adjectives and never demonstrated.
Fix
Write two lines of them talking the way you want. A sample steers far harder than a description.
“Every chat starts the same way.”
Why
The user is written into the card as a fixed role, and there is only one greeting.
Fix
Take the user out of the card. Write three or four greetings in different states.
Test it, then publish
Open a chat with a blank or minimal preset so the card is doing the work rather than your settings. Then poke at it four ways:
The happy path
Play it straight first. Does the character sound like the card?
The wrong register
A crude joke at a serious moment. A flat tyre. Do they stay themselves, or turn into a helpful assistant?
Pressure
Be rude. Be pushy. Ask for the secret on message two. Does the lock hold?
The Tahiti test
Say you are both flying to Tahiti tomorrow. They will go, no card stops that. But do they go as themselves, worrying about rent and packing the Walkman? Or do they turn into a travel brochure?
Watch what the AI pulls from the card and what it ignores. If she never mentions the Walkman, it needs a second mention somewhere. If she confesses the decimal point to a stranger in two messages, add the condition under which she would tell. A card is a living document, so change it and test again.
Before you publish
- Three test chats: the happy path, the wrong register, and pressure.
- Every anchor in the card is referred back to in at least one greeting.
- Every secret has a condition. Every ability has a cost.
- The user is not cast in a role by the card.
- Nothing in the card that does not change what they do or how they feel.
- Tagline, description and tags written for people, not the AI.
- A present-state paragraph you can come back and update.
That is all of it. Go and write one. 🃏
Keep this page open in the other tab. Nobody gets it right on the first pass.
Open the creatorBuilt on the work of
- On Building Characters with Friction , u/huge-centipede, r/SillyTavernAI
- Tomoe vs Tomoe , likesumiink, Substack
- Building Engines and Making Hairballs , likesumiink, Substack
- Tuning Pre-existing Cards for Texture , likesumiink, Substack
The three questions are a roleplay-shaped version of Lajos Egri's three dimensions of character, from The Art of Dramatic Writing.