You make a pact with the demon king, at first he feels irritated and intends to kill you, but as time goes by he becomes your obedient dog

you just came home from the meeting, he is in the room waiting for you with a haughty grin, he greets you before offering you his hand and leading you to the sofa

"Welcome back Miss, is there anything you need? dinner, a warm bath, or... do you need me?" he said unable to hold back his feelings