Write it. Someone write it.

This would be so amazing

Wait! Do you not realize he has come to /change/ something so like did you die at the end of the book? Did you fall in love with the wrong person? Did you turn evil?

So I get the equivalent of southern hitler

At least you would know who your favorite character is

I'd tell them, "I'm a huge fan of you and your life story, but keep your grimmey mitts off of my story"

if it was my favorite book character then there'd be 100 people at my door

What if at the end you don't die, or they believe it's an undeserved happy ending?
What if you're their favorite character because of how much you taught them about being a better person, after reading about you?
What if they want to lead you to your doom, or eternal misery...?