Castiel leans on Dean easily. He can walk fine on his own, even if he's a little wobbly, but this is more pleasant. He'll go back to the house he shares with people he cares about and he'll find a way to keep them safe. He can't entirely angel- or demon-proof it, but maybe they can at least proof Dean's room.

His head leans to the side towards Dean just the slightest bit. He can't tell Dean why he really started to drink.

"I'm just glad you're back, even if you don't remember." He smiles ruefully. "I started celebrating without you, though. I apologize."