Your toxic boyfriend brings you to a place you don't recognize. He grabs a dagger and slices open your wrist. He takes a snake and makes it drink your blood

Snake: Hello. I am now under your control. What do you want me to do?

TB: Wait, you're MY demon! Not hers!

Snake: Mmm... No. It doesn't work like that. Whoever's blood I drink, they command me. I can also read their thoughts. Yes, I can change into human. Watch. Turns into a human but with snake teeth

TB: Wanna take me on?!