Dean rested on one elbow as he rocked his fingers inside Sam, rubbing fingertips against his prostate, watching his face until Sam spoke, making every bit of Dean ache with pleasure at the thought. A little groan escaped and Dean was glad Sam dragged him into the kiss. Slipping his tongue between Sam's lips, he moaned into his mouth, rubbing relentlessly at Sam's sweet spot.
He broke the kiss long enough to catch his breath. "God, that's so hot, Sammy," he murmured, kissing him again once more before dropping down between Sam's legs, Dean slid his tongue against his brother's cock, sucking on the head with a low moan and swallowing down as much of it as he could, his hand holding onto the rest of it.
Rocking his fingers harder, Dean hummed around his dick, aching to get inside him but equally desperate to just keep at this until Sam lost his mind.