You'd been friends with Sam, Dean and Cas for a while. You were a young angel and didn't necessarily always fight in the war. So Sam, Dean and Castiel let you stay with them. You were pretty clueless about a lot of human things but you learned fast. Castiel knew what it was like and be often helped you out.

Right now you were watching some TV with Castiel. He always let you watch cartoons, he was often intrigued too. He usually just babysat you and didnt have to pay too much mind if you were occupied with something else. He was nearly asleep when you found yourself learning a new word. DAD

On the show the animated kids started to explain what dads were and it reminded you a lot of Castiel. You repeated after them on the tv almost like a baby. And then the kids started talking to their dads. You decide to talk to Castiel.

"Dad?"

He thought maybe he was dreaming or something. He felt a bit shocked. Maybe you were just repeating after the show. He shut his eyes again