Dean and his mommy have become inseparable, to the point where Dean's chest literally aches when he's away from him for too long, at school, in boxing training, with friends, or those times when his parents (the lovebirds) would go out on dates, or spend some alone-time together.
It's the reason why weekday afternoons are now near-sacred to Dean, it's his time with mommy, before he gets busy with homework, or before he gets picked up, and dropped off to training or to see his friends.
Dean doesn't hold back during those times: He doesn't stop touching his mom, hugging, fake-wrestling, horsing around, "accidentally" touching Sammy's breasts or groin or ass when he does, lying in Sammy's arms, or even on his lap, running his hands through mommy's hair, nuzzling his jaw, his neck, smacking kisses on his hands and fingers, rubbing their noses together and a few times, kissing him right on the lips. Mommy basks in the attention and love. Of course he does, Dean thinks. Dad told Dean that Sam had a tough childhood; his father was mostly absent and when he was not, he didn't pay much attention to his kids, and Sam's mom was anything but warm. It's part of the reason why Sam is openly affectionate - overcompensating for a starved childhood and avoiding his mother's parenting model in the process. Unlike his parents, Sam prioritizes bonding with his family, and is programmed, not just to give love, but take love where he can take it; he's like a bottomless pit, always craving what he grew up missing. And of course, he worships at the altar of his husband and kids.
Besides, Dean is convinced his mommy was already his; he just has to ease him into the realization. And so far, his mommy is very responsive.
Right now, they were sitting on the living room sofa again, in their typical position, Adam in his mommy's arms nursing, with Dean half lying on top of his mom, practically straddling a thigh. With the way they're snuggled, Dean's own chest is squishing Sam's currently unoccupied breast.
Dean has convinced his mom to lose the shirt while he's nursing, saying things like "easier," "you run too hot mommy when you're nursing, this way you won't sweat in it," yadda yadda. Sammy would still keep his bra on, and just free one boob at a time to feed Adam, but Dean is not complaining. As long as there's progress, he's good.
Right now, Dean's cheek is touching Sammy's collarbone skin-on-skin where his head is lying. Sam's scent is heavier, more filling. Two of Dean's fingers are absently circling the skin around where Adam's mouth latched on and suckled. Dean was lost in the sight before him. He's a visual person. He likes looking.
His mommy is relaxed, and from time to time, he'd turn his head and kiss Dean's forehead.
Sometimes when they're in a different position, when Dean is just laying a head on Sammy's shoulder, instead of half-blanketing him like he is now, he would gently knead Sammy's free milk-swollen breast as he watches Adam, or talks with his mom. Dean likes feeling up the nipple poking through the bra, caress it, play with it until it's fully erect. He'd feel feather-light shivers running through his mommy's body as he does. If Dean wasn't listening to every small response, registering every twitch and ripple, consumingly tuned in to his Sammy's body as he is, he would've missed it.
Sometimes, he would finger his Sammy's navel, or run the pads of his fingers along his treasure trail, from the navel and down to the rim of his shorts or sweats, then back up again. Sometimes, he just rubs his mom's belly in soothing circles, like his mom would do when he has a belly ache. Other times, Dean would just rest a hand near his mom's groin, his pinky rubbing absently, stroking against Sammy's genitals.
"I'm gonna miss those," Dean says now, as he touches where Adam's lips meet skin. "When you wean Adam off," he elaborates.
"Trust me, sweetheart, mommy won't. They're heavy, and they're painful sometimes."
"How long did I nurse on them when I was a baby?"
"Almost two years. You were weaned early, and you didn't give me any trouble at all. Unlike Mister Adam here who I think is gonna give me a hard time," Sam says, his tone full of love.
Adam is around 16 months old, so thankfully Dean will get to enjoy the sight of his mommy's C-cups for a bit longer. He can only hope Adam proves hard to wean off. He knows some kids keep nursing until the age of 9 or 10, especially in traditional households. His grandma once told him that his uncles and dad nursed for roughly 4-5 years, and that was considered too little time back then.
Sammy told him that his breasts will eventually get smaller when he stops breastfeeding, "I'll never be flat-chested again, your body changes forever, you know, after having children. But it won't be as big and full as it is now, thank God."
But Dean won't start mourning them yet.
"I don't remember," Dean says.
"What? Being breastfed? No one does, sweetheart."
A pregnant pause.
"Mommy, can I get a taste?" he blurts out.
His mom just laughs softly.
"Please?"
"Someone's curious, alright. You're probably the big first kid I've heard of who's not terribly grossed out by the idea," Sam says.
Dean scrunches his nose in genuine bewilderment and looks up at his mom, "Why would I? It's food for my baby brother. It'll help him get big, like me. And you have a nice chest, mommy. Breastfeeding is beautiful." Your titties are beautiful.
"Aww, baby, now you're waxing lyrical," Sam says, leaning in to press a peck on the tip of Dean's nose.
"So can I?" Dean insists.
Sammy huffs a breath, and "yeah, sweetheart. Why not?"
Dean starts to sit up. Sam looks a little surprised.
"What, now?"
"No, mommy, when I'm in college," he smiles. "Of course now!"
"Alright," Sam says, sits up himself and eases Adam off his breast for a moment. Dean helps him hold Adam while he unclasps his bra and takes it off completely.
Dean can immediately sense his mommy is feeling somewhat self-conscious at getting topless, and he avoids looking at Dean.
Dean doesn't understand why: Sammy's tits are very pretty, and his nips are hard and pointy, they're fucking gorgeous. If it were up to him, he'd make his mommy walk shirtless around the house.
Scratch that, if it were, his mommy wouldn't be allowed to put clothes on inside the house. He'd have him barefoot and butt naked 24/7.
When Adam is settled again, Dean doesn't waste a breath and swoops in to take the other breast in his mouth. He begins sucking right away, like he'd been thirsty for weeks.
He's on a high, right now, doesn't even believe he's getting away with this. Probably hurting mommy from the sound of it but Sammy's whimpers only excite Dean more, his dick now taking interest and pushing against his zipper.
He hopes his mom doesn't notice this side-effect.
"Easy, Dean," mommy says moments later and squeezes his shoulders with his free hand to get his attention. Dean looks up at him as he continues to suckle, his mouth still working, but Sammy's eyes are squeezed shut, and his breathing is coming out a little faster. He's biting on his lower lip.
"Don't bite the nipple, baby. Wait-Dean!" He pushes him away, suddenly. Dean pulls back a little, a thin line of spit connecting his mouth to the hard nip he just parted with. He regards his mom innocently.
"You're hurting mommy, De," Sam says.
"What should I do then," Dean asks, inching closer so now his lips are brushing against the bud as he speaks softly, "to make you feel good, mommy." His voice is vibrating against the nipple. He adds, "I mean, so you'd feel less pain."
"You're sucking too hard, sweetheart," Sam holds Dean's head against his bare chest, with one hand. "Open wide ... wider, honey," Sam says then pushes the tit back in. Dean latches on again, but this time keeps his mouth slack, waiting for more instructions. "Don't just take the tip. Don't latch on just the end, De. The nipple should be touching your tongue, not pinched between your teeth." Sam explains. Oh mom, you're killing me here.
Dean begins sucking, as told. "Yeah, that's right, just put enough pressure there to get some milk out. Don't rush, and don't bite down. Th-that's good, baby."
Dean is enjoying this too much, his arousal at mommy's brand of accidental dirty talk is making him a little dizzy. He couldn't help the moans that just escaped him. His hips hitch too despite his efforts to control his down-stairs brain.
Before his mom suspects he's nearly bringing himself off as he does this, with all the moans and twitching, he takes his mouth away, and mutters "it's delicious, mommy," as innocently as he can. Then goes back and continues suckling.
He doesn't do it for longer though. His mom soon pushes him away, telling him to leave some for Adam, doesn't put the bra back on, but puts on the shirt. While he does, Dean adjusts himself so his arousal is not visible.
Sam looks somewhat uncomfortable. And when he's settled back, he doesn't pull Dean back in his arms. He just ruffles his hair and asks him if he's got homework to do. It's Sammy's polite, loving way of dismissing him.
Dean kind of expected this; when things become a little strange, like when Dean started making a habit of kissing Sam's neck or his jaw, or when he started placing soft pecks on his lips, wires are crossed a little for Sam, and he'd get momentarily confused or he'd falter, sted of reciprocating or thinking nothing of it.
But every time, he'd end up embracing the change in dynamics.
Dean knows his mother is enjoying all this as much as he.
The first time Dean kissed him full on the mouth, Sam didn't exactly kiss back, and asked humorously, "what was that for?" Dean just shrugged, not wanting to make it look like a big deal, like he didn't know where the question is coming from, like something is up with Sammy if he's asking. Dean just told him, he "just felt like it." Can't a son give his mommy an innocent, chaste kiss?
The last time they kissed? It was his mommy who puckered up and presented his lips for kissing. Dean was ecstatic. He gripped mommy's waist and gave him a big old wet kiss. No spit was exchanged or anything, but Dean parted his mouth a bit as he kissed. He consciously pressed his lips a few seconds too long, the tip of his tongue prodded Sammy's sealed lips, then nibbled on his lower lip dragging it with him. When Dean pulled back from the kiss, Sam's lip slipped from his mouth with a soft pop.
The kiss was yummy. Dean had raised his game, and it can only get better from there.
So now, Dean decided he won't read too much into Sam's discomfort at the breastfeeding experiment; perhaps his mommy did realize on some level that it was slightly erotic for Dean. Perhaps Sam sensed his arousal, smelled it, or caught a glimpse of his growing bulge before he had a chance to adjust. Or not. His mommy is very innocent, and he worshiped him.
In all cases, Dean knows like he knows like he knows that he won't be denied this if he asks for it again (and he will).
Call it an Alpha hunch.