AU generator for your own characters
Choose a setting, add your cast and see how they behave when the world is different.
High school AU
Saturday detention in the school library. Three students must finish one group project before 3 p.m. (Everyone here is a teen — keep any feelings to crushes and banter.)
In shortCastfic is an AU generator that plays the scene: pick a setting like coffee shop or high school, add your original characters, each played separately and knowing only their own secret. You direct, then rewrite it as prose or a screenplay. 1 free scene without an account, then 1 a day with Google sign-in.
How to put your OCs in an AU
- Pick an AU template, such as high school, coffee shop or fantasy quest.
- Add your characters. Say who they are in this version of the world.
- Press play, and steer with narration if the scene drifts.
- Keep the scene as prose or a screenplay, and save a memory to each card.
Settings to start from
- High school AU: a club room after the last bell.
- Coffee shop AU: a broken espresso machine and one free table.
- Fantasy quest: a map, a debt and a party that does not trust each other.
- Time loop, secret identity, locked in a room, found family.
Same people, new setting
Ravi is a cautious engineer in his usual setting. In the high school AU he is the newspaper club's treasurer. Lena is a stage manager turned student council rival.
| Character | Line |
|---|---|
| Ravi | "The club budget is forty dollars. I've spent thirty-nine. Do not ask me about the dollar." |
| Lena | "I'm not asking about the dollar. I'm asking why the dollar was a glitter pen." |
| Ravi | "It was a very good pen." |
Ravi's secret, which Lena does not know, is that he wrote the anonymous column she keeps quoting. The scene steers toward that.
What stays the same
Cards stay the same across AUs, and memories carry over, so a character who learned something in the coffee shop remembers it in the next setting if you want them to.
How Castfic compares
| Castfic | Sudowrite | NovelAI | Talefy | Type.ai | ChatGPT | |
|---|---|---|---|---|---|---|
| Free tier | 1 free scene without an account, then 1 a day with Google sign-in, plus a free Daily Scene | Free trial, no card; no ongoing free plan | Free trial: 50 text generations | Free account | Free plan with limited credits | Free plan with usage limits |
| Cheapest paid plan | $4.99 for 15 scenes, or $7.99/mo | $10/mo | $10/mo | From $1.99 | $8/mo billed yearly | $20/mo (Plus) |
| Characters keep separate secrets | Yes, each is played separately | — | — | — | — | — |
| Scene to prose or screenplay | One click: prose or Fountain, 4 styles | Writes prose | Writes prose | — | Writes prose | Prose if you ask |
| OC memory across sessions | Written back to each character card | Story Bible | Lorebook | — | — | — |
| All-ages by design | Yes, 13+ with filters on | — | — | — | — | — |
Competitor details are from each product's public pages in October 2026 and may change. Product names are trademarks of their owners; Castfic is not affiliated with them.
Frequently asked questions
Do I need to write a whole world?
No. The template gives the setting and an ending beat. You add the characters and, if you like, a line of narration.
Can I write my own AU setting?
Yes. Write your own setting and ending beat instead of using a template.
Can I use a fandom AU?
Yes. Write your own version of the fandom's characters into any AU. We don't preset canon characters, and Disney, Marvel, Nintendo and Pokémon characters are blocked.
Can the same OC be in several AUs?
Yes. The card is reusable, and you choose whether earlier memories carry over.
Does it cost anything?
1 free scene without an account, then 1 free scene a day after signing in with Google, plus the free Daily Scene.
Try it with your own characters
1 free scene without an account, then 1 free scene a day after signing in with Google, plus the free Daily Scene.
Try a scene free