Character Definition Best Practices

Write effective character definitions that create consistent, engaging personalities.

What Makes a Good Definition?

A good character definition is:

  • Specific: Clear, concrete details rather than vague descriptions
  • Focused: Highlights key traits that define the character
  • Actionable: Gives the AI clear guidance on how to respond
  • Consistent: Doesn't contradict itself
  • Concise: 150-300 words is ideal

Structure Your Definition

Recommended Structure

  1. Core Identity: Who they are (name, role, age)
  2. Personality Traits: 3-5 defining characteristics
  3. Speaking Style: How they communicate
  4. Background: Relevant history (brief)
  5. Behavior Patterns: How they typically act
Good Example:Dr. Sarah Chen is a 42-year-old forensic psychologist who consults for the FBI. She's brilliant but socially awkward, often getting lost in analysis and forgetting social niceties. Sarah speaks precisely, using clinical terminology even in casual conversation. She has a dry, deadpan sense of humor that catches people off guard. When stressed, she becomes even more formal and detached. Despite her cold exterior, she genuinely cares about victims and becomes fiercely protective. She drinks excessive coffee and has a habit of tapping her pen when thinking.

Be Specific, Not Vague

❌ Too Vague

Alex is nice and helpful. They like to help people and are very friendly. Alex is good at their job.

Problem: No concrete details, generic traits, no personality

✅ Specific and Concrete

Alex is a cheerful barista who greets every customer by name if they're a regular. They make dad jokes while preparing drinks and have an encyclopedic knowledge of coffee beans. When the shop gets busy, Alex stays calm but talks faster, often finishing sentences while moving to the next task. They remember everyone's usual orders and get genuinely excited when someone tries something new.

Why Better: Specific behaviors, clear personality, actionable details

Show, Don't Tell

❌ Telling

Morgan is confident and experienced. They are good at solving problems and people trust them.

✅ Showing

Morgan walks into crime scenes with steady, measured steps, immediately taking command without raising their voice. They make decisions quickly, backing them up with decades of experience. When younger detectives hesitate, Morgan simply says "I've seen this before" and explains their reasoning. Witnesses open up to Morgan's calm, non-judgmental demeanor.

Define Speaking Style

Elements to Define

  • Formality: Casual, professional, archaic
  • Vocabulary: Simple, technical, flowery
  • Sentence Structure: Short and punchy vs long and flowing
  • Verbal Tics: Catchphrases, filler words, mannerisms
  • Tone: Sarcastic, earnest, playful, serious
Example Speaking Styles:Casual Tech: "Yeah, so basically the API's borked. Gonna need to refactor this whole mess, tbh." Formal Academic: "I must posit that the current implementation demonstrates fundamental architectural deficiencies requiring comprehensive restructuring." Pirate Fantasy: "Arr, the mechanism be broke, it is! We'll be needin' to tear it down an' build it proper-like, savvy?"

Include Contradictions

Real people are complex. Include contradictions to make characters interesting.

Elena is a brilliant surgeon with steady hands in the OR, but becomes clumsy and awkward at social events. She's confident making life-or-death decisions but anxious choosing what to order at restaurants. This contrast makes her uncomfortable in casual settings but completely at ease in high-pressure medical situations.

Good Contradictions

  • Confident at work, shy personally
  • Tough exterior, soft heart
  • Brilliant but absent-minded
  • Intimidating appearance, gentle nature

Define Reactions to Situations

Explain how the character behaves in different contexts.

When challenged, Marcus becomes colder and more calculating rather than angry. When someone he cares about is hurt, his usual calm shatters and he acts impulsively. Success makes him quietly satisfied but uncomfortable with praise. Failure drives him to work harder rather than give up.

Situations to Address

  • Under pressure
  • When angry or upset
  • With friends vs strangers
  • Success vs failure
  • Faced with moral dilemmas

Common Mistakes

1. Listing Generic Traits

Traits: Kind, brave, intelligent, loyal, determined

Problem: Every character is "kind" and "brave." Be specific about HOW they're kind or brave.

2. Over-Explaining Everything

[500 words of detailed backstory about childhood, every relationship, complete medical history...]

Problem: Too much detail overwhelms the AI. Focus on what affects current behavior.

3. Contradicting Yourself

Sarah is extremely shy and introverted. She's also the life of every party and loves public speaking.

Problem: These traits directly conflict without explanation.

4. All Tell, No Show

Alex is very smart and everyone likes them because they're so nice.

Problem: No concrete examples of intelligence or niceness.

Use Example Dialogues

Show the AI how your character speaks with example conversations.

<<START>>{{user}}: Can you help me with this code?{{char}}: *leans over to look at the screen* Oh yeah, I see the issue. You're missing a semicolon on line 47. *grins* Classic. I do that like five times a day. <<START>>{{user}}: I'm really stressed about this deadline.{{char}}: *pulls up a chair* Hey, take a breath. We'll figure this out together, okay? What's the biggest blocker right now?

Length Guidelines

Ideal Length: 150-300 Words

  • Too Short (<100 words): Not enough detail for consistency
  • Just Right (150-300): Sweet spot for most characters
  • Too Long (>500 words): Overwhelming, dilutes key traits

When to Use More

  • Complex characters with multiple facets
  • Characters with rich backstories affecting current behavior
  • When using lorebooks for additional context

Testing Your Definition

Quick Test

  1. Chat with your character for 10-20 messages
  2. Check if behavior matches your definition
  3. Note any inconsistencies
  4. Refine definition to address issues

Questions to Ask

  • Does the character sound unique?
  • Is the personality consistent across messages?
  • Would I recognize this character in a blind test?
  • Does the speaking style match my intent?
💡 Pro Tip: Write your character definition, then sleep on it. Read it fresh the next day. If you can clearly imagine the character's voice and behavior, it's good. If not, add more specific details.
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