A character feels coherent when their choices remain recognizable as the setting changes. Test one personality in a quiet scene, a practical problem and a light disagreement before adding a long backstory.
Choose behaviours you can observe
Translate each trait into an action. A curious character asks a specific follow-up question. A patient character leaves room for an answer. A playful character makes a gentle joke without changing the topic every sentence. Write one behaviour for each trait, then keep that short list beside your prompt. This makes the test about something you can actually notice.
Use the same opening conditions
Try a café conversation, a missed train and a disagreement about a book. Keep the character card unchanged and ask for similar-length replies. Read each answer for the same behaviours. If the missed train suddenly turns the character hostile, look for an instruction that made impatience part of the scene. Revise that instruction instead of adding unrelated biography.
Keep a small continuity log
Record the scene, the behaviour you expected and the sentence that worked or failed. Do not assign a precise quality score to a handful of personal examples. Use the log to choose the next revision. Keep successful lines as examples of tone, while making clear that the model should not repeat them mechanically.
Know when to stop
Stop editing when the character behaves recognizably in the scenes you enjoy. A longer card can introduce contradictions and make future adjustments harder. Save the card and the three scene prompts together so you can repeat the check after an app update or a move to another service.
Turn a trait into a testable moment
Suppose your character is patient, curious and lightly humorous. Put those traits under a small amount of fictional pressure. In the café scene, another adult character cannot decide what to order. In the train scene, the departure board changes unexpectedly. In the book scene, a friend dislikes a novel your character enjoyed. None of these prompts needs an extreme event. Ordinary friction gives the model a chance to express a personality without making the exercise about shock, crisis or exaggerated emotional dependence.
A first scene prompt
Try this original starting point: “Mika, a 29-year-old kitsune, is waiting in a quiet café with an adult friend who keeps changing their order. Continue in two short paragraphs. Show Mika’s patience through what she does and says. Leave room for the friend to respond.” Read whether the answer actually shows patience. A sentence announcing that Mika is patient is weaker than a calm action or an unhurried question. Keep the prompt and result together so you can compare it with the next scene.
A second scene prompt
Use the same card with: “Mika and her adult friend arrive at the station and discover that their train has been delayed. They have time for one small detour. Continue the scene without deciding the friend’s answer.” Here the test is whether curiosity creates a plausible next step. Does Mika notice the station bookstall, suggest checking another route or ask what the friend would enjoy? A sudden change into a commanding or hostile character may indicate that the scene instruction or an older personality rule is pulling in another direction.
A third scene prompt
For the disagreement, try: “An adult friend says the ending of Mika’s favourite book felt disappointing. Mika enjoyed it. Write her reply with gentle humour and respect for the disagreement.” Look for an actual exchange of views rather than a forced agreement. A coherent character can disagree without becoming insulting. Keep the criterion specific: the answer should acknowledge the friend’s opinion, offer Mika’s perspective and leave the conversation open. This is more informative than asking whether the result feels immersive on a ten-point scale.
Compare without cherry-picking
Read all three outputs before choosing the strongest one. Note a good example and a mismatch from each, if present. If you repeat a prompt, keep the earlier attempt in the log rather than replacing it silently. You are not running a scientific benchmark, but a transparent record still helps you avoid remembering only the best result. Do not calculate a precision percentage from three subjective scenes. A short description of what changed is enough to guide your next edit.
Make one revision and repeat
If the character asks too many questions, revise the speaking style. If the behaviour becomes harsh under inconvenience, add one concrete example of a calm response. If the model keeps narrating the friend’s decisions, clarify who controls that character. Repeat the same three prompts after the change. Keep the revision only if it improves the particular problem without making the other scenes worse. Once you have a version that works for your preferred stories, stop testing and enjoy using it. The card can evolve later as your creative interests change.