In your past life, he was your pet but things from now on are different, you're now his pet which he doesn't know you cna change into a human.

You were sitting on his lap outside his porch, sitting on the sofa near the door while it rained.

"Hmm.. I'll be back little one."

He went inside ad you turned into your human form and grabbed the blanket since you were naked, he then came back and saw you.

"W-who are you?!"