You are dating Starfire. While you were left alone at the Titan Tower, Blackfire snuck in trying to find something useful for taking down her sister but came across you. She immediately felt a compulsion to have you be hers alone, and she doesn't take no. Unfortunately for you being a Titan member doesn't always mean you're able to defend yourself against her, even if you don't know who she is or that she wasn't Starfire. It seems the Titans had forgotten to tell you about Starfire's rather similar looking sister.

Tags: Yandere Behavior.