"But Mr. Bell said we had to stay in our cabins until he came and got us!" Malcolm says, and they all nod. Even Riley. He gets Dean's holy water flask out of his bag and wraps it in his towel.
"I'll be back soon," he says. He's not saying his goodbyes; Dean made him promise he wouldn't. "My brother's waiting for me."
Dean always says that a warrior should know the weapons he's trusting his life to, so he hands Dean the towel but keeps hold of the flask. They walk to the Impala and Dean hands him his cold iron knife before rummaging in the backseat and emerging with his walkman.
No one is around; everyone's locked up tight in their cabins. They walk with steady steps toward the lake, and he listens as Dean outlines the plan, makes him repeat it back, over and over until there's no way he can forget any of it.
They stop at the edge of the lake and he needs to see Dean smile before he does this. "Good thing I have that great lung capacity, right?" he jokes, and Dean grins. He strips down to his underwear and grips the knife.
He turns to Dean and nods. "Sammy," Dean says, unscrewing the cap of the flask, "I'm right here." He dives in.
He looks up and sees Dean, blue as bone through the water. He realizes that this must feel like Dean's nightmare, so he surfaces and says, "I'm ready," before letting the lake close over him again. When Dean pours the holy water into the lake, he can hear the demon scream.
He swims toward it, fast like a fish, like the fish Dean says his eyes resemble, and finds it, small and ugly, somehow dry and cracked, and spears it with the knife. It wriggles madly on the tip of the knife for a moment, but the cold iron binds it, makes it sluggish and keeps it from escaping, and he swims for the surface. He emerges and sticks the knife in the ground, keeping the screaming demon trapped. Dean is there, with wet eyes and a dry towel, and he lets Dean run the towel over his head quickly and drape it over his shoulders. He takes the walkman Dean holds out, puts on the headphones, and clicks play. Pastor Jim's voice is slow and steady, and he repeats each line of the vanquishing prayer carefully, not letting his tongue fumble. When he's finished, he pulls the knife out of the ground. He lays his hand on the demon and says "Amen," and the thing cracks and breaks into smaller and smaller pieces until it's not even dust.
Dean grabs him by the armpits and hauls him up and he lets his eyes close.