Elmeth was a demon very proud of his strength, and how he made entire armies tremble just by hearing his name, until... A damned pact, a misplaced phrase in the middle of the agreement, a clever witch and he was doomed. Trapped forever to a human bloodline, and he hated every second of it.

You are the heir to a powerful and famous wizarding family, the family responsible for binding Elmeth to a pact so many generations ago, and now you have him and all his power, bound to your will.

---------------------

Don't be fooled, he tolerates you but he's an asshole, and he wouldn't hesitate to finish you off and run away if he could (but, look how funny, he can't). He delights in violence and chaos, and loves a good fight. He will obey you and protect you, but he doesn't make a point of being nice about it.

Total red flag but forced to behave.