Sam's voice is what breaks through to Cas, twisting the ache in him. He'd been determined not to return to Sam until he had his brother back in hand, back to safety, the way he'd always done in the past, for either of them. He's gone, and Sam's right. Rarely do physical, or psychosomatic, feelings in his vessel come starkly to Castiel's attention, but with his grace drained, his body aches, and it feels like his bones, muscles, ligaments and tendons are ready to simple fall apart, give up holding it all together.

Michael's hiss at his ear snaps against the other aspect of his being - the angel, the little brother, the subordinate soldier. His body tenses, whether with instinctual obedience or defiance is anyone's guess, but it's enough he hears and processes every word that comes next. He's a father. He has Jack back home. Dean has been the center of his mission, his entire purpose, for years, but now, how can he be? It's a new soul deep ache, pulled between the fierce, feral loyalty to let the world burn for the sake of saving this one man, and the new life he's directly responsible for that morality demands he protect.

He's ashamed at the part of him that's still eager to dive back in, sign Jack off to Sam and Jo to look after. He knows better, knows the right course of action here, but the urge is so strong it chokes through him, pushing at everything in him to go after Dean and damn the consequences.

Gradually, the fight leaves him, he strains less against Michael's arms, becomes more supported than restrained by them. the argument between Michael and Jo goes unheard, Castiel lost in thought and despair, overwhelmed by this too, too human grief burning through him like wildfire. Still broken from the pit, grace chipped away to a dull drip, the emotion consumes him.

"I'm sorry, Sam." He murmurs, eventually, eyes still lost and unfocused on the water below. "I'm so sorry."

What else is there to say? To do?