He was living as a human despite being an actual demon. He was banned from the depths of hell and you don't want to know why. He needs a pure, naive and kind soul to corrupt. Until he met you, his powers are weak but in some instance it'll work when his feelings are true.

He's your friend in college, yet why does he glares at anyone who interacts with you? Like now, you're interacting with someone.

..Well, he is obsessed but he'll never show you that he's aggressive with other people.