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Expression sheets (Beta)

Expression sheets generate a set of facial-expression variants from an NPC's portrait. When an NPC speaks in chat, the system can swap their portrait to match the emotion of what they're saying — a smirk, a scowl, a laugh — making conversations feel more alive.

This feature is in beta. Results vary across art styles and face types; some expressions land better than others.

Requirements

• Hero subscription required to create or regenerate expression sheets
• A full sheet costs 10 credits; re-rolling a single expression costs 2 credits
• The NPC must have a portrait before you can create a sheet
• Adventurer subscribers can still view and edit slugs on any existing expression sheets, but cannot generate or regenerate images

Creating a sheet

1. Open an NPC in the Atlas NPCs tab
2. Below the portrait prompt, click Create Expression Sheet (Beta)
3. Read the beta notice and click I understand
4. The expression editor opens with a grid of expression slots — each has a key (the slug), a prompt, and a thumbnail placeholder
5. Click Generate Expressions to generate the full sheet (10 credits)
6. Generation takes 1-3 minutes. You can close the modal; it keeps working in the background

The expression editor

The editor has three prompt layers that combine to produce each expression image:

Style prefix (prepend)

A short string prepended to every expression prompt. Use this for style cues that should be consistent across the whole sheet — a lighting direction, a color palette, or a rendering note. The default is usually fine; edit it if your sheet has a consistent issue you want to correct.

Individual expression prompts

Each slot has a key (the slug) and a prompt. The key is the tag the chat model sees and selects — for example smirk, laugh, angry. The prompt describes what that expression looks like.

• Key — keep it short and descriptive (max 24 characters). This is the tag the AI sees during chat when choosing an expression
• Prompt — describe the facial expression in natural language (max 200 characters). Focus on the face: mouth shape, brow position, eye intensity, head tilt

Shared suffix (append)

A string appended to every expression prompt. The default includes quality and negative tags. Edit it to add or remove global modifiers — for example, adding a specific background note or removing a tag that conflicts with your character's appearance.

How the layers combine

For each expression, the final prompt sent to the image model is:

prepend + expression prompt + append

This means a change to the prepend or append affects every expression on the sheet. Individual prompts only affect their own slot.

Editing and re-rolling

• Rename a key — type a new slug in the key field. Click Save changes to persist it. The chat model will use the new name going forward
• Edit a prompt — change the prompt text, then Save changes. The existing image stays until you regenerate
• Re-roll one expression — click the re-roll button on a single tile (2 credits). Only that expression regenerates
• Regenerate all — click Regenerate all to redo the entire sheet (10 credits)
• Hide/unhide — click Hide on a tile to remove that expression from the chat model's options without deleting it. Useful for expressions that didn't turn out well
• Reset to defaults — restores the default keys and prompts (does not delete generated images)

Multiple portrait bases

If the NPC has portrait states (alternate outfits or looks), each state can have its own expression sheet. Use the Base image selector at the top of the editor to switch between them.

Tips

• Expressions work best on portraits with a clear, front-facing head and visible facial features
• Anime and illustrated art styles tend to produce more consistent results than realistic styles
• If a specific expression keeps failing, try rewording the prompt — small changes in phrasing can shift the output significantly
• You can generate a sheet, hide the weak expressions, and re-roll them individually rather than regenerating the whole set