#mtf!sam

Dean can smell it. they'll just be sitting next to each other and he'll go from thinking about something else to sudden awareness that his little brother is wet

Sam's only been on t for a couple months and he's a squirmy horny mess so much of the time, walking around with a hard dick and a slippery cunt

"what're you thinking about?" Dean doesn't have to look over to see Sam blush bright red

"uhm"

"c'mon, kiddo, you can tell me" Dean also doesn't have to look to reach over and slide his hand into Sam's briefs and feel the heat of him

it's deceptive because Sam's folds can close up so demurely so only his dick pokes out, but when Dean teases a finger into his slit, Sam is a fragrant, slimy mess. he clenches his thighs tight and whimpers

"was thinking about this" Sam admits. "about your hands smelling like me, 'bout you smelling me on you when you eat later"

"fuck, Sammy"

I have been thinking about this since you sent it! mostly about tall lesbian power couple SamJess. maybe other people have known (or suspected), but Jess is the first person to treat her like a woman. to talk hair and makeup, to take the lead and make her feel small, to fuck her like a woman (Jess is obviously a top. fight me.)

Jess is the first person to talk to Sam about what she wants instead of assuming. she asks about the shit people have formed their opinions about without asking, like assuming she'll want to change her name to "Samantha" (no, she fucking hates that and isn't sure if she wants to change her name at all) or that she hates her penis and can't wait to have it cut off (she doesn't hate it, but isn't sure if she wants to have it forever)

Jess asks. more importantly, she remembers Sam's answers. she asks the important things like does Sam want her to touch her breasts and lick her clit and finger her? does Sam want Jess to come into the exam room with her at the doctor's? does Sam want her to correct people who use the wrong pronouns or let Sam make that decision on a case-by-case basis?

oh god, a Sam who hates her penis more than anything. hates how it looks, hates how it smells when she sweats. hates how big it is and how prominent the vein in it is and how it feels like a treacherous snake in her hand when she bathes. a Sam who runs and fights and reads and tries not to think about sex at any time because she feels sick when she gets hard because it forces her to remember it's attached to her body. forever.

hates how there's no winning. she feels it when she runs but she has to run so she's too tired to be horny. she has to touch it when she showers after she runs but if she doesn't shower she can smell it

when she was a teenager, she'd take the blades out of razors and cut tiny careful parallel lines on the shaft. never too big because she was scared that Dad or Dean might notice them at some urinal someday and she doesn't want anyone to know about the cuts because then they'll know about her

she takes up smoking so she has an excuse to have a lighter and when she really, really needs it, she'll flick it on in a rest stop bathroom until the metal surface gets really hot and press it deep into the sensitive skin

tbqh I think this is how canon would be with tgirl Sam. he does so much weirdly sexual feminizing of Sam already that if he could talk about how "he always knew she was a girl, look at those big titties how could anyone miss it" and if he could talk about her shaving her long-ass legs and "how hot she'd look in a mini skirt"... he would

also he'd be waaaaay intrusive about the most visible/permanent aspects of transition. if he noticed her tucking, he'd demand to see it an only be half joking. if she had facial surgery or electrolysis, he'd be all up in her business about it. she should've had more or less or he expected the results to be different

he'd also say those really shitty things that lots of cis dudes do about how "he'd be able to tell her original gender" even if he didn't know her because he's so fucking perceptive or whatever

been thinking about this for days and here's where I've landed (let's proceed with the assumption of established wincest and that Sam stays Sam/Sammy and uses exclusively she/her pronouns):

I don't think the tone of their relationship would change much. the "brotherly" teasing and all that stays, with the modification that Dean now says shit like, "always knew you were the girl, Sammy" and "your big naturals"

but Dean is not above using Sam's transness in a fight the way he uses everything else about Sam. he's completely capable of misgendering Sam on purpose to hurt her. we're talking looking her dead in the eyes and calling her "it" and "freak"

I think overall he'd try, but that he wouldn't always know what that should mean. like he'd catch it when he fucked up her pronouns but would still say "when you were a little boy." Sam would probably hide a lot of her medical transition plans/thoughts/choices because of it and they'd stumble onto shit they didn't expect to be weird but it still is (think Dean hyperfixating on whether Sam will get bottom surgery and if her pussy will "work like a real one")

imagining a Sam who's been on estrogen for years, who's had a vaginoplasty, who's transitioned socially and a Dean who's worked hard to show up for her who is thrown for the biggest fucking loop when Sam asks him to call her "little brother" and to tease her about her body. because he's constantly on guard against doing that shit by accident and he's not sure if he's comfortable looking at beautiful, confident, all-woman (Dean's exact phrasing because he's still a dick) Sammy and maybe doing damage that'll take them months to fix

they don't do it in that moment but there's a day when she's being exactly like her bratty angsty teenaged self and Dean throws her down on the bed. when she tries to get up, Dean says, "uh uh, little brother, not until I say" and it gets her fucking w e t