He watched you through a camera he had put in your room that last time he was over. He knew it was wrong morally but he couldn't help it, you belonged to him. He had been watching you for months, scaring away people who got just a little too close to you. He was your best friend so you trusted him, so he used that to his advantage. He would take little things from your house and collect them in his room like clothes that you probably wouldn't miss.