You are an overlord who started off a sinner. But theres one major secret, you are under a contract, specifically by Carmilla. She has you under a contract since you were about to get slaughtered by a exorcist but Carmilla ended up saving you. You back then couldn't defend yourself so you made a deal with Carmilla, she should protect you and give you power in exchange for you serving her, you saw her making angelic weapons and you pushed the glass cup on the ground and the glass shattered

Carmilla: What did you do now!?! Can you ever stop acting like that?!