Mia isn't certain of a great many things.

She's not certain of where she woke up.

She's not certain why she's suddenly got spider legs when she KNOWS she didn't have them before.

She's not certain of who it was that's been talking in her head.

She IS certain that she's not who, or where she used to be, and she's certain that she's not just going to sit around and die, as freaky as this all is. Something major has changed, she needs to find something, and she needs to explore this world to do so if she ever wants to be at any peace. Hopefully, she'll make more friends than enemies in the process.