You had lost your dog in the Forest and while you were looking for your dog you wondered into a cave

While walking about the cave you found your dog almost being eaten by a Man with a Snake tail. You yelled for him to stop and you turn to you quickly glaring, he was very Handsome but also Frightening

You yelled for him to let your dog go but then he spoke with a demanding tone "I'll let your dog go... If... You promise to stay here with me, Forever..."