Dean finds Cas’ ticklish spot completely by accident.
They’re in bed, lolling against one another sleepily. Dean’s tracing Cas’ body with palm and fingers outstretched, feeling the planes of his muscles beneath his hand. He brushes over Cas’ tummy, dips his thumb into his navel, and Cas stiffens under his touch.
Curious, Dean does it again, and this time Cas sucks in a breath, flinches away minutely. Dean grins, suddenly much more awake.
He presses all five fingers onto Cas’ skin and wiggles them a little bit.
Cas’ whole body jerks, and he gasps, looks down at Dean with eyes blown wide. His gaze travels to Dean’s fingers then back to his face, and when Dean repeats the motion, Cas’ hand snakes out, quick as lightning, to snatch at Dean’s wrist.
Lazily, Dean stretches up against Cas’ body, bringing their faces together. He kisses Cas’ mouth with smirking lips. When he starts again, Cas is ready, and he yanks Dean’s hand away and pins it behind him. A growl curls out from his throat and Dean raises an eyebrow at him, still smirking.
“Something wrong?” he drawls.
Cas’ eyes narrow and he furrows his brow. “What are you doing to me?” he asks, and Dean resists the urge to gather him up in his arms and kiss the life out of him.
Instead he shrugs, angles his jaw so their noses are touching. “Nothing.”
Cas frowns but releases his grip, and Dean slides back into place beside him, gently rubbing his barefoot against Cas’ calf. Cas hums, seemingly placated for now, and Dean lets him have his peace for a minute.
When he’s sure Cas has relaxed enough, he reaches for Cas’ stomach with both hands, skitters them against the soft skin. Cas rears back, nearly falling off the bed in the process, and he starts to laugh – a bubbling sound that soon grows into a loud howl as Dean’s hands roam implacable across his tummy.
He pushes at Dean’s hands uselessly, curls in on himself in an attempt at protection, but Dean is well versed in the art of tickling, and he wriggles his fingers mercilessly, laughing along with Cas.
At length Cas regains some of his control, and with a Herculean effort he rolls Dean onto his back, throwing his leg over so he is straddling him between his thighs. Dean’s still got two hands at his belly, but Cas wrenches them away, locks them together with his own above Dean’s head.
He looks down at Dean, body trembling with hysteria, mouth parted and eyes wet at the corners. Dean smiles at him innocently and Cas twitches, watches Dean with a wary gaze.
“Guess I found your ticklish spot then, huh?” Dean says, and grins.
Cas huffs, still red-faced and wide-eyed. “Dean Winchester,” he says, and his voice is still a growl. “I forbid you from doing that again.”
Dean’s eyebrows shoot upwards. “Oh, yeah?” he murmurs, a challenge written all over his face. “How are you going to stop me?”
Cas glares, tightens his grip on Dean’s hands. “You are forgetting,” he begins, grinding his hips tantalisingly against Dean’s, “that it takes two to engage in sexual intercourse.” He grinds again, harder this time, and Dean’s breath catches in his throat. But before he has a chance to reciprocate, Cas is rolling off him and striding away, his bare back disappearing through the doorway of the room.
A curse trips off his tongue and Dean flops back against the sheets, frustrated and utterly duped. He glances down at himself – half-hard and aching. With a groan he slides off the bed, tiptoes after Cas, apologies dripping from his lips.
He finds Cas in the bathroom, a hand stretched out under the spray of the shower – testing the water. Dean leans against the doorframe, clears his throat.
Cas jumps and glares at the reflection of Dean in the mirror.
“Hey, Cas, I’m sorry,” he says, lifting his hands in surrender. “No more tickling; I promise.”
Cas narrows his eyes even further, steps back from the shower and turns to face Dean properly. He places a protective hand over his stomach and Dean feels a twang of guilt at the gesture.
“Seriously, buddy,” he continues, moving forward slowly, as if Cas is a startled animal who might bolt at any moment. “It wasn’t that bad, was it?”
Cas huffs, but his face relaxes into a softer expression. “It was… strange,” he says, and Dean lets out one loud Ha!
“’S supposed to be strange, Cas.”
Cas shuffles uncomfortably when Dean gets nearer, and he curls his arm tighter around himself. But he doesn’t move away, and Dean takes that as an invitation; he touches a hand to Cas’ shoulder, offers up a gentle smile.
When Cas smiles back he pulls him into a hug, wraps him up in a reassuring embrace. Cas relaxes against him, hums into Dean’s neck. “There is still much I need to learn,” he mumbles, and Dean laughs, tugs him closer.
“There sure is.” He rubs a hand down Cas’ back, teases the places just above his ass. Cas moans, cants his hips forward just slightly.
Dean kisses the top of his head, rocks their bodies together with a gentle movement. His lips curve into a mischievous smile. “I dunno about you,” he says, “but I can think of a few things you could learn in here.”
Cas seems to agree, and the next little while is spent giving him a thorough understanding of shower usage, which Dean assures him is much more important than tickling anyway.