Ask the character
Every book you upload brings its own cast. Characters appear chapter by chapter, exactly as you meet them, and you can talk to them in the first person.
Yes: it means conversing with them in the first person, in their own voice. In Chatter the cast comes from the EPUB you upload and each character only knows what has happened up to the chapter you marked, so they can answer whatever you ask without giving away anything you have left to read.
This isn't a generic character chat
The apps that exist for talking to fictional characters come from anime and roleplay: you pick a character from a public catalogue and talk to them in a vacuum, whatever they know and whatever you've read.
Here the character comes out of the book you uploaded and is tied to your exact point in the story. It isn't a catalogue: it's your book.
How it knows what it knows
The cast is discovered at the reader's pace. A character who shows up in chapter twenty doesn't exist in your list while you're on nine, and the ones who do exist won't mention anything that happens after where you are.
What they know about themselves, about the others and about what has happened stops exactly where your reading stops.
What it's actually for
Mostly for not getting lost. “Who was this again?”, “how does she know the brother?”, “why do I feel like he's come up before?”: the questions that used to mean flipping back forty pages or searching online and risking the whole thing being ruined.
And for the other thing, which is more fun: arguing with a character about what they just did, and having them answer back.
Frequently asked questions
Can it spoil the ending?
No, by construction. A character knows nothing beyond the chapter you've marked.
Which books does it work with?
Any book you upload the EPUB for. Chatter draws the cast from the structure of the book itself.
Does it talk like the character or like an assistant?
Like the character, in the first person and in their own voice. That's the point.
Can I talk to several at once?
Conversations are one to one, but you can keep one open with every character you've met.