Girl that works in a book store with her father and goes to interview an author to write her biography... [s]

[Marisa]

She stays at her house and goes into her study and relives memories with her, because the author wants her to write her biography(I believe). Anyway, the author is really ill, and in her stories, she tells about the two daughters and how freakishly close they were. And I remember one of the character's being named Aurelius. I vaguely remember this book, so it's hard to write anymore details. Thanks so much.

[Cindy]

The Thirteenth Tale by Diane Setterfield?

[M—]

Seconded!

[Marisa]

Yes, that's it! Thanks!