When Dean finds out Cas has never experienced a blowjob, he jumps right into rectifying that, and he may skip the part where he should tell Cas some basic blowjob etiquette. So, Cas can’t really be blamed when he starts to climax and thrusts as far into Dean’s mouth as he can, because honestly it’s instinct. Cas is horrified when Dean chokes and pulls off of him, coughing up come and saliva. Dean assures him it’s okay, and he just wasn’t expecting it, or it would’ve been fine.
The second time Dean gives Cas a blowjob, Cas is a bit more shy about it. He keeps his hips pinned to the wall behind him the entire time Dean works his cock. It takes a long time for Dean to get him to the edge, because Cas fights it so hard. When he comes this time, he jerks back and pushes Dean’s shoulder away. Dean’s face gets covered in come, and he chuckles while Cas blushes scarlet. Dean doesn’t stop laughing until he’s cleaned his face and leans in to kiss Castiel.
The third time, Dean knows he has to take a different approach or Cas is just going to be frightened of blowjobs for the rest of his existence. So, Dean starts with something Cas is familiar with. He works him open nice and slow with gentle fingers. He pushes into Cas with deep steady strokes. None of it is rushed. Dean’s purpose is to relax Cas, and it works. They rock against each other without any real push to finish, and they share soft kisses and tender words. Cas’ body is pliant and humming with pleasure when Dean pulls out slowly and kisses his way down Cas’ torso.
Cas loses a little of his calm when Dean slowly licks up his shaft, but Dean assures him that it’ll be okay. He moves back to working Cas’ hole with slick fingers while he takes as much of him as he can in his month. Soon he’s pressing three fingers into Cas in time with the bobs of his head, and Cas grips the sheets as he babbles incoherently in a tongue Dean doesn’t understand. He can feel Cas teetering on the edge, and he prepares himself. This time when Cas comes hard, Dean doesn’t even flinch as he swallows it down.
He continues to work Cas through his orgasm. When Cas comes down, Dean slowly slips his fingers out of Cas and finally lets his cock slip out of his mouth with a wet pop. Then he crawls back up Cas and kisses him thoroughly while be pushes back into him and continues his languid strokes. ”Now, aren’t blowjobs great?” Dean asks as he hitches Cas’ legs a little higher around his hips for a better angle. Cas let’s out a pleased whimper, and Dean smiles widely as he gives him another kiss.