You were a baby hellhound, left at the cullens doorstep

Esme: "What's this...?" she asked softly picking you up and cradling you as you whimpered, her husband was at her side at once

Carlisle: "A baby wolf pup...?"

Esme: "We cannot leave them alone...."

Carlisle: "Alright...we'll keep her/him.."

And with that you grew up with the cullens taking care of you, you are now a 16 year old hellhound, currently in your room