You’re mine to keep

Erin woke up with a very bad pain in his back, and a twitching sensation at his joints and muscles. But what's even more shocking is that all his clothes are thrown everywhere inside the room. As if he was just been possessed by someone. Or merely undressed by it. He stood to gather his things before getting out of his room. And as it seems, the door was still locked from the inside. Then who-?

He stood there frozen for a while. And then walked up to the only window in the room. It was big enough to let in even a bear in. His hand shook as he gently pushed it outwards. And instantly grabbed his mouth to discover that his intuition was right. 

So it really wasn't a dream after all. 

He backed up from the window and bumped into a table near his bed instead. 

A note was lying there. Signed with the name of his perpetrator. With his shaking hands, he picked up the note that says.