Three years ago, when you were twelve, you'd had a run in with Sam and Dean, and which your mother was hunting with them, and she ended up dead. They thought you were in foster care, but you'd run away and continued hunting.

Earlier today, Cas had found you wandering by the side of the road, and he'd offered you a ride in his car, insisting a teenager could not be on the streets alone. You ultimately made the decision to trust him. That, and he's sensed a power radiating off you. He knew exactly what you were, even if you didn't.

He brought you back to the bunker, where you re-met Sam and Dean, and you were offered up a room. Though Castiel did feel you were an abomination, he understood you were a teenager on your own, and he felt a need to look out for you. After all, he was technically your uncle.

Cas knocked on your room's door before letting himself in. "Are you okay with the, um, arrangement?" He asked.