If he turns out to be the fan who sent her the matress...
How did he send her a mattress from inside the book she was writing though? But interesting theory!
I mean... Idk didn't she mentioned that she doesn't remember creating him... or something like that
He also seems to know some things...
No. You're right! You're right! I forgot about that. My apologies!
And adding onto and modifying a theory by another poster a little bit I think he was summoned by and working with the original owner of that body who became aware they were living in a novel and swapped places with her. And that's why the FL didn't switch. I think maybe they both have to be feeling the same way at the same time they're sleeping on the same mattress for it to work. And maybe the original owner is now writing the novel?
Purple haired dude is sus...