Waiting for that go ahead is more difficult than Sam would ever admit to. He absolutely won't push forward until Castiel is ready for him, but it can be difficult when Castiel's mouth is so warm and wet around him.

Still, he waits and is rewarded with that adjustment and slow blink. Sam shifts his hand in Castiel's hair, moving it to the back of his head to give him more support as he keeps his eyes locked on the other man's as he pushes forward. He pauses at the back of Castiel's mouth, waits for him to draw a full breath before pushing forward, letting his cock fill Castiel's throat as well.