Finally, the promised first of the polybros x demon sisters headcanons that no one asked for!! I'm gonna start with the older brother x little sister pair! Polyester and Kneesocks!
I'm gonna start with regular headcanons and add a few nsfw ones at the bottom 😏, but before this I want to clarify that either this or the other pairing work under these other set of headcanons:
Both Ramie and the polybros are still on leave from their duties, which means their whole hatred for demons is less extreme, but their whole superiority attitude remains
The polybros are very much aware of Junior and aren't thrilled he exists, but also stated they weren't going to do anything against them either, which is more than enough for Panty and Brief 🤷🏽♀️
For obvious reasons and math, this also means I headcanon Bastard as being younger than Junior, but not by much, maybe anywhere in between a year or two.
I'm taking S2 finale implication that Garter has apparently died for good this time and Stocking is now in charge of the church, but has yet to fully take on the 'Sister Stockiel' role.
While I'm doing this for my crack theory involving Bastard being the resulting child of these pairings, you don't have to agree with that part in particular and just read it as a regular shipping headcanons.
Polyester x Kneesocks
It all starts because Polyester happened to be at one of the places where Kneesocks coincidentally works at, let's say it's a dinner and he's there to pick some take out and she is on shift, at first he only thinks it's weird there's a demon working there but it's only until Kneesocks mentions not expecting to ever see him again, he finally remembers she's not just any demon, she's one of the daughters of the King of Hell, and outright mocks and asks what the fuck she's doing working at a place like this.
Kneesocks only scoffs that she's is technically banished from hell due to siding with the angel sisters during their confrontation with their father, and she wants to earn her living at the church and not be a freeloader (and also because she gets free food, unlike Garter, Stocking is an awful cook), and remarks that it's obviously not something a spoiled angel brat could understand.
Polyester takes offense on that statement but is unable to fight her on it since, for starters, he is using his dad's credit card to pay for the food which he definitely heard Kneesocks chuckle when she noticed which actually managed to make him flush with embarrassment, and he just takes his food grumbling and leaves in silence.
BUT when Kneesocks is getting off work, she's surprised to see him outside the dinner as if waiting for her, and she starts summoning her weapon because he can't be having any good intentions... Except he kinda does? He was trying to give her a ride to the church, because he's trying to be nice not because he wants to prove her wrong (except he does, he won't let a demon be a better person than him lol)
Kneesocks accepts, more out of exhaustion than to reassure him and can't help but notice that unlike Panty's car, his is actually clean and well-maintained, since she fully expected Polyester to be just as messy as his cousins she's low-key impressed and says as much, which prompts him to info dump her about how him and his brother take very good care of it because it was a gift from their dad leading him to praise Polyurethane's mechanic skills and she can't help but gain a a bit of respect for how good of a brother he seems.
Polyester hears her chuckle again, and for a moment he thinks she may be making fun of him again, and he's ready to call her out on it, but the words die on his tongue when he catches her smiling in his direction, not a scornful smile like in the dinner, but a genuine one that his mind almost betrays him into thinking it's... cute, and he turns around because he feels the flush start at the base of his neck.
Originally Polyester had planned to drop her a little farther from the church not wanting to risk being seen by Stocking, but he drives her right towards the entrance instead, and when she gets out of the car, she sighs and thanks him with a polite bow and admits that "maybe he isn't that much a brat" and smiles again, wider this time, he swears he see a halo around her, even though it makes no sense, her being a demon after all, but he reached his way home way faster than normal because he felt an inexplicable rush of energy and revved up a little too much, when Polyurethane asks him why there are wheel marks on the entrance he is suspiciously quiet but humming happily to himself
Ever since then, Polyester would not so subtly vote to get food from the same dinner every time his brother suggested take out, and instead of asking for delivery he would offer to pick it up himself and always took a little too long more than they both knew it took to get there, and never agreed to let Polyurethane do it himself or even when he suggested to come with him and maybe eat there instead of take out, he gets even more suspicious when one time he accidentally grabs Polyester's food and he realizes it looks... pretty, it's weird to describe food like that, but the way it's arranged neatly, an extra portion of everything and it looked fresh out of the pan, when his brother rushes a little too fast to switch the plates and avoids looking at him, he thinks he has his answer, well he supposes some pretty waitress has a guardian angel now.
Of course it's because of Kneesocks, who little by little warms up to Polyester and even starts to expect his presence on the days she knows he orders take out, memorizes his usual order and makes sure to pack it herself and if he sometimes offers another ride home after work, or if he keeps her company during a slow shift, she welcomes it, Scanty immediately notices that Kneesocks has the look a girl in love and doesn't dare to ask questions because she doesn't want to ruin the experience for her and only makes teasing comments because she enjoys the cute way she blushes and fidgets.
They don't have things like a first date or anything of the like, but they have a bunch of little "firsts", tiny touches and held gazes, when he gave her his jacket because she shivered in the cold, when he bought her favorite blend of tea, or she left him a little note in his food, the first time he held her hand, and finally their first kiss happens in a rush of the moment when Kneesocks gave him a peck before getting out of his car and he was left dazed and frozen in spot for a couple minutes.
⚠️🔞N / S / F / W Headcanons 🔞⚠️
As already mentioned, their whole relationship wasn't very formal or following through specific steps, it was very sweet but also a bit clumsy, unplanned and awkward so their progression to intimacy followed a similar pattern:
Their first "real" kisses, happened almost always initiated by Kneesocks, but she felt compelled to do it, because she could see how badly he wanted to, the way he would look at her lips while she talked, how his hand lingered on hers longer than usual, how his body shifted to stand just bit closer, or the heated looks he send s her way, maybe without even realizing, but that she finds adorable either way, she only needs to hold his chin and make him look at her for him to turn into putty in her hands and kiss her back in full, holding onto her tightly and not stopping until they're out of breath, and maybe a little trail in between 😳
It goes down in a slow but steady spiral from then on, if they looked obviously crushing before to outsiders, now they look downright lovesick and probably prompting a lot of comments of "get a room you two!" from the rest of the staff in her work, of course none of them actually expects that, prim, proper and ladylike Kneesocks absolutely uses her breaks to make out silly with Polyester, sometimes in the back, or in his car.
The start to move from just kisses, when Kneesocks notices he has a "little problem" after another session, and rather than give him a time to "calm down" she moves her hand just above his belt and starts rubbing, and poor Polyester has his mind going blank due to how amazing she feels and does feel a little embarrassed that he didn't last too long (virgins amirite?) but she doesn't care, because she enjoyed watching him lose control.
Of course this means he wants to "return the favor", but she is not just ready to let him touch her there, and instead brings his hands to her breasts because "girls like to be touched there too" and of course he has no complains and marvels at how soft they feel, and can't get enough of the little noises he can get out of her when he brushes and pinches in the right spot.
"Can I... see you?" He asks one day, because he can't bring himself to ask her to undress, just the top he swears but if she doesn't want to it's totally fine, by the time he finishes talking Kneesocks shirt is already open and halfway down and he can't help but stareee... which makes her giggle a she moves forward and makes sure to have her breasts rest just on top of his chest and asks him if he "also wants a taste", and he can't nod fast enough.
Of course this means that their make out sessions are now practically low-key dry sex, with all the touching, partial nudity, the humping, rubbing and the "hand and mouth stuff" but even then they ever fully cross the line into fullblown sex, it bothers them both because Kneesocks knows that losing virginity is a big deal for angels and for Polyester, despite having done so much, it doesn't sit well with him to go all the way in the backseat of the car, it's tacky and think she deserves better, if he's doing this, he wants to do right by her.
So they book an hotel room (due to Panty's suggestion of a motel room, but even that felt too trashy for him) and he makes sure to pay for the best room available, and wants to make sure to make her feel special, and she does feel flattered by all of it, and didn't even seem to mind being seen with her by the employees, because a part of her still feared that he saw her a his "dirty little secret"
Of course they finally unwind completely the moment the door closes behind them, and their first time happens with her on top of him, with slow but deep thrusts against her while holding onto her for deaf life because he can't stop himself now, of course once is not enough and they both have inhuman stamina and end up trying different positions and surfaces and learning what the other like more and made them finish.
He brought protection, of course he did, always the careful one, but when they both got into the heat of the moment, and both of them are inexperiencied, sometimes protection fails, sometimes they both forget and it feels too good to remember after the first unprotected round with him balls deep inside and her feeling too warm and wet, and the little box lays forgotten on the night stand, and it's probably fine because is not like either of them have ever heard of a an hybrid offspring between an angel and a demon, and they keep at it for the rest of the night...
(and if you wanna follow my crack theory, you can guess this is the day Bastard was conceived 🫣)