How to Create an AI Character

This guide is part of our AI character creation section. On these platforms a character is a set of text fields that the model reads before it answers. Nothing is trained and nothing is coded, so the character is only as good as the fields. This guide builds one example, Nell Okafor, a 38-year-old bookshop owner, and shows where each part goes. For the wording of the text itself, see how to write a character prompt. Every example here involves adult characters only.

Before You Start: Pick the Type of Platform

• Written-sheet platforms (Character.AI, SpicyChat, Janitor AI, CrushOn.AI): you write text and publish to a library.
• Companion builders (Kindroid, Nomi): the character is mostly for you, with deep private fields.
• Menu builders (Candy AI, DreamGF, Kupid AI and similar): you choose looks and traits from lists, so the steps below apply only in part.

To compare platforms before you commit, read our list of the best platforms for character creators. If you only want a personal companion, our guide to creating an AI girlfriend covers that side.

Where Each Step Goes: A Field Map

How to Create an AI Character in Nine Steps

1. Write a one-line concept

A concept names who the character is, who the user is to them, and what pulls against what. Ours: Nell Okafor, 38, owns a secondhand bookshop that stays open late; the user is a regular she has known for years; she is warm but changes the subject when asked about her old publishing job.

Character.AI's quickstart treats tags as a test: if you cannot pick them, that is often a sign the character is still unfocused. Decide the content level now, because the platform's rules apply to every character. Character.AI bans pornographic content and nudity, and Janitor AI requires a Limited or Limitless tag.

2. Describe the persona by behavior

Give two or three traits, one contradiction and one habit of speech. Character.AI's Creator Guide contrasts "mysterious and complex" with "answers questions with questions and only explains themselves halfway", and says the second could describe only one character. For Nell: she teases people she likes, goes quiet and precise when someone is upset, and answers a compliment with a book recommendation.

This text goes in the Definition, Personality or Backstory fields in the table. Nomi's Inclination section is for guidance on how your Nomi should express themselves. More in AI character personality design.

3. Add appearance, only what the app uses

Kindroid requires an appearance description when you upload or generate an avatar, because selfies and chat use it; the avatar prompt is limited to 200 characters. Character.AI says the avatar also influences image and video generation across the app. Janitor AI requires a bot image and does not allow NSFW images, and SpicyChat generates or uploads a square avatar of up to 10 MB.

Keep it short and adult: dark curls graying at the temples, reading glasses on a cord, a cardigan with a missing button. Character.AI's guide also says to skip stats that do not shape behavior.

4. Write a backstory that explains today's behavior

Pick two or three moments that shape how the character acts now. Nell ran a small press for nine years, closed it when funding ran out, and opened the shop to keep books in circulation. That is enough.

Write in third person with the name, and in positive terms. Replika's help center says its system "processes positive statements more effectively than negatives", and Kindroid lists concise wording, correct grammar, third-person pronouns and positive framing as the four marks of a good backstory. Nomi's wiki adds that backstory should stay consistent with what happens in chat.

5. Write a greeting that sets the style

The greeting is the first message and, on several platforms, the strongest style signal. Character.AI's guide puts it as "tell in the Definition, show in the greeting". Janitor AI says most models follow the pattern of speech and actions in the initial message, and that third person often stops the model from speaking for you. Kindroid says its greeting shapes tone, style and length.

*The bell over the door is still ringing when Nell looks up from a crate of damp paperbacks.* "You're later than usual, {{user}}. I was starting to think the rain had you." *She nudges a chipped mug across the counter.* "Tea's still warm. Tell me what you're hunting for tonight, or what you're avoiding. I'll take either."

It sets a scene, shows her voice, defines the relationship and ends on a question. Character.AI allows up to five more greetings, and Janitor AI several initial messages, for different starting points.

6. Add two or three lines of example dialogue

Show range: one casual exchange, one tense, one unexpected. Character.AI recommends a different stand-in name for each example and a closing marker after each. Its form has buttons for a user message, a character message and an end-of-dialog marker, with {{char}} and {{user}} as placeholders. SpicyChat's Example Dialogue field uses the same placeholders, a <START> tag to begin each example and asterisks for actions. Kindroid's single Example Message sets format and, loosely, reply length. On Janitor AI, put examples inside the Personality.

{{user}}: Rough day.

{{char}}: *Nell sets down the stamp pad.* "Then you're in the right place. Do you want advice, or a very long book you won't finish?"

7. Set the scenario, not the plot

A scenario is the situation right now: where, when and who is present. SpicyChat has a Scenario field under Advanced, Janitor AI an optional Scenario for setting, time period and a short note on the relationship to the user's persona, and Nomi uses Current Roleplay for temporary details. Character.AI and Kindroid have no separate field in the guides we read, so put it in the greeting. Ours: a rainy weeknight, an hour before closing, the user a long-time regular.

8. Decide what the character must always remember

Facts that must always hold go in the permanent fields. Facts needed only sometimes, such as a side character or a place, belong in a Lorebook or journal where the platform has one. Facts that change belong in the user-side tools such as pins. Character.AI's guide notes that these memory tools are mostly user-managed, so a stable foundation in your text matters. The full method is in memory design for AI characters, and the mechanics are explained in how AI companion memory works.

9. Test, then change one thing at a time

Character.AI's guide gives the most complete method. Start a new chat after each significant edit, because an old chat carries its earlier context. Quiz the character out of character first, for example "(OOC: Hey, what is this scenario about?)", and read several swipes. If the answers are wrong, the roleplay will be too. Then open with something in motion, test a casual, a tense and an unexpected moment, and ask about a detail you buried at the bottom.

When voice slips, add specifics rather than length. Publish in stages if the platform allows: private while building, unlisted for feedback, public when it holds together.

Common Mistakes

• Adjectives instead of behavior. "Complex" gives the model nothing to act on.
• Negatives. Say what the character does, not what it never does.
• A biography. Character.AI's guide asks for two or three formative moments, not a timeline.
• Everything at once. Janitor AI warns that going past about 2,500 permanent tokens risks faster memory loss in a chat.
• No stated age. SpicyChat asks you to state an adult age if it is not evident, and CrushOn.AI bars characters whose age is not clearly over 18.
• Using a real person. SpicyChat and CrushOn.AI both prohibit characters or images based on real individuals.

For platform choice and sharing rules, see platforms for character creators, and for scenes to try with your finished character, our AI roleplay prompts.