Okay but imagine Dean asking Cas to drive because he’s too tired or too hurt or just because. And when Dean hands him the keys, Cas is a little overwhelmed, because Dean might as well be saying “I trust you with my whole life”. Cas wants to hug him, or kiss him, or tell him that he understands and he loves him too, but instead he just takes the keys.
Dean stretches out in the back and Cas drives so carefully, always protecting Dean. When Dean falls asleep, Cas realizes that Dean must feel safe, and again Cas wants to hold him, wants to wrap his wings around him. But he knows he isn’t allowed to do that yet, so he just keeps driving, heart so full he thinks is might burst every time he glances at Dean in the mirror.