Responses
Killing herself = her brother being left alone
Killing the detective because she won’t eat = keeps her in his grasp longer/she won’t fight him anymore to save the detective
So his obsession starts with her resilience against the moms/students at the school who tried to get her fired and ruin her life. He saw a sparkle in her fire power… so when she demonstrated that she still has that firepower and resilience to literally kill herself and stop him from having any reason from harming her brother it made him realized she still has that same sparkle. So he targeted the detective and is trying to possibly make her care for herself to prevent harm from coming to the detective ? Maybe it’s not that simple lol but it makes sense to me