The spell hits Cas square in the chest.

He’s frozen for a moment—mouth open in an almost comical sort of way—then he goes tumbling backward, over the railing and out of sight.

Sam’s yell is drowned out by Dean’s own roar of fury—and he fires, three, four, five shots, until the chamber is empty.

He doesn’t even check to see if the witch is down before he’s barreling forward, screaming Cas’s name into the dark.

“Cas!” He yells. “CASTIEL!”

The water churns, bubbles spouting to the surface, and Cas’s head follows a moment later. He doesn’t look hurt, in fact, he looks like dropping fifteen feet headfirst into the water was merely a mild inconvenience. The knot of fear and worry in Dean’s throat loosens immediately, and he growls, slamming his hand on the railing.

“Dammit, Cas,” he shouts down at him. “What the hell were you thinking? Tryin’ to get yourself killed?”

Castiel blinks water out of his eyes, scowling up at him.

“Yes, Dean, I’m perfectly alright. Thank you for asking.”

Dean says a few choice oaths under his breath, pushing back from the railing. Let Cas fish himself out, then.

He walks back over to where Sam is inspecting the body of the witch, still muttering.

“Didn’t need to ventilate the guy, Dean,” Sam says dryly, before standing, wiping his forehead with the back of his hand.

“Yeah, well.” Dean tucks away his gun in the back of his jeans. “Nothing wrong with makin’ sure.”

A clatter from behind them prompts both Winchesters to turn around. Climbing up and onto the bridge, looking remarkably like a drowned rat, is Cas. He’s still scowling, water dripping from his coat, collecting in puddles around him.

“You okay, Cas?” Sam calls. “He got you on the last one, right?”

“Yes,” Cas confirms, walking closer. Dean resolutely avoids looking at Cas, especially where his white dress shirt lies plastered to his skin. “I am intact, though. Physically.”

“Shouldn’ta rushed him like that,” Dean mutters. “I had the shot.”

“And yet the witch is dead,” Cas replies coolly. “So I’d say we accomplished the goal, hmm?”

Dean glares at him.

Sam clears his throat, abruptly jumping in. 

“Guess we’ll never know what the spell was, then.”

He nudges the dead witch’s leg with his foot.

“If Dean hadn’t gone all Dirty Harry on him, maybe we coulda found out.”

Dean rolls his eyes, and leans over, grabbing the dude by the arms.

“Hey. I say, no harm, no foul. You good, Cas?”

“Yes,” Castiel replies immediately. “I’m fine.”

“Good. You get his legs.”