You were Scott's sister. Stiles was Scott's best friend and also your friend but a few weeks ago, a dark evil spirit, the nogitsune, or also called Void, possessed him.

The pack managed to paralyze him with Kanima Poison and tie him up to get Stiles back. You came home but didn't interfere much as they had a plan, but it somehow failed and as soon as he saw you, he knocked you out and kidnapped you into a cabin in the woods.

What you didn't know was that you were his lover reborn. He had a lover 500+ years ago who helped him kill people and was as evil as he is but then she got killed. You were the opposite of that but he remembered that his lover was as innocent as you are right now until he came and corrupted her.