Soul mate marks, but instead of a mark, once you and your soulmate turn 20, you both start swelling up with each other's baby, and once you're due you can't give birth until you've gotten intimate with your soulmate.
🟢 Childhood sweethearts, both excited when they begin to swell up once they're both 20, weeping in delight and relief when they both go into labor with each other's at the same time, just as they'd always hoped they would.
🟢 A young couple, who hit their due date and never go into labor. A scenario that would normally lead to a break-up and heartache, this young couple places bets on who's going into labor first, and spend their free time going out and getting laid, making out with each other, and caressing each other's gravid bellies, while random strangers fuck them senseless.
🟢 A pair of soulmates who have been pregnant with each other's babies so long, they've given up on meeting each other. As they get older and older, they get more pitying looks from whomever they meet, as it's clear their time is running out to find their soulmate. By the time they meet at the retirement community center, they've both given up on giving birth to their little ones. At least, until one night at a community pool party gone wild, when both their waters break in the hot tub. The community rallies around them, helping the first-timers through their labor and reminiscing about their first time giving birth with their soulmates.
🟢 Someone who never swells with child, having accepted their lack of a soulmate a long time ago, enduring the pity of those around them for being destined to be alone. One day, when they've already hit their mid-50’s/early 60’s, they realize they've got a steadily growing baby bump. At first they're elated to have a soulmate, until the horror dawns at how much younger they are. They resign themself to simply be happy to feel their soulmate's child growing and kicking within them, planning on never becoming intimate enough with someone young enough to be their soumate. About a decade later, spent contentedly round with their child, they find themselves falling for their new neighbor. In their 30’s, they're kind, caring, and also heavy with child. One night, after a neighborhood BBQ, their younger neighbor flirtily insists on waddling home with them, and by the morning they're both holding each other up, bellies pressed against each other, while they crown around each other's babies.
🟢 A sheltered person from a controlling bigoted family, who was always taught that a soulmate bond was only between two people, finds themselves swelling up so quickly after their 20th birthday that it's clear to everyone they're knocked up with multiples. Their parents disown the "shameless whore,” and they're left on their own, rapidly becoming so big it's obvious at first glance that they 1) have more than one soulmate, and 2) won't be able to walk on their own for much longer.
🟢 Polycules in various stages of pregnancy. The oldest happily swelling up with one, surprised to find themselves swelling up with another… then another. In the medium age group of the polycule, they find themselves swelling first with twins or triplets, then later on swelling again. The youngest of the polycule turns 20 to find themselves growing rapidly with quints. The others, either groaning when they realize another big baby is beginning to grow alongside the quads already squished in their womb, or if they've already connected with others in the polycule and given birth to their babies, somewhat frustrated that they've just gotten small enough to move around again only to discover another baby growing in their belly.
🟢 Someone meant to find love more than once, suspecting what might happen when they're carrying twins, and their first soulmate is only carrying a singleton. Perhaps they fall out of love and separate amicably, or perhaps their first soulmate tragically passes away. They hold their crying children at the funeral, a hand resting on their belly, not quite sure yet if they're ready to feel the hope their unborn child's kicks want to inspire. Maybe it'll be a few years while their first children are still young, maybe it'll be later once their children are grown and moved out of the house. But even through their grief, they know that someday they'll find love again.
🟢 A couple who have given birth to each other's babies, but both find themselves still full term with a singleton, struggling to take care of two rambunctious toddlers with their gravid bellies, with equally rambunctious unborn babies impatiently kicking away, slowing them down. Once a month, they try to hire a babysitter, get dressed up, and hit the town in the hopes of finding their twin-filled third.
🟢 Sex-repulsed aroace people, who have been told all their lives that only sex with their soulmate can induce birth, happy to stay big and pregnant as long as it means they don't have to have sex. Many are pleasantly surprised to find themselves rapidly going into labor after a deeply intimate conversation with one of their favorite people in the world (who is also in labor with them).
🟢 Soulmates who give birth to each other's babies, and then keep breeding like jack rabbits. They're pregnant so often, that sometimes old acquaintances and distant family members will see them and assume they still haven't found their soulmate yet, only to be startled when their attention is drawn to the small sports team of kids behind them.
🟢 Clubs that try to only hire drink-tenders (because a lot of ‘bars’ in a very pregnant world are non-alcoholic, but offer a space for people to gather, satisfy pregnancy cravings with bar snacks, and maybe find their soulmate) who have found their soulmate already/aren't pregnant, because too many times they've had their drink-tenders go into labor mid shift. Sometimes more than one drink-tender, and once a drink-tender went into labor multiple times in one night.
🟢 Clubs having medical staff on hand to help people through their labor, and it's become common to have more private, comfier, delivery rooms in the club for the newly found soulmates to continue to bond while they're in labor.
🟢 A polyamorous person, who has multiple soulmates who are not soulmates with each other, who seems to be constantly growing and giving birth, spending their early to mid- 20's full of at least triplets, at their smallest. When they meet each of their soulmates, who mostly are carrying only one to two babies, with only one soulmate carrying triplets, they look gargantuan in comparison, carrying sextuplets at their biggest.
🟢 Soulmates in a will-they, won't-they situationship, who keep skirting the edge of becoming intimate enough, physically or emotionally, to induce labor, but shying away at the last second, with their bellies hanging low on their hips. Constantly feeling practice contractions that border on the real thing, their babies heads so low on their pelvis, threatening to batter through their cervix at any moment, always on the edge of their water bursting, chest leaking milk in preparation to feed their babies. And yet, neither of them manage to realize they're soulmates (for a while at least).
🟢 Someone who's tired of comments on their flat, soulmate baby-less, belly. So they hatch a half-baked, not very thought through plan, to just go out and get knocked up. Their plan works, and they realize, too late, that everyone will be expecting to meet their soulmate after they go into labor, but they still won't have one. Their regret worsens when they discover they're expecting twins. At some point they come clean, and find everyone around them surprisingly supportive, and apologetic for making them feel so pressured they felt they needed to do that. Imagine their surprise, when they give birth to one baby, and the other one stays put, content to stay safe and snug in their womb until they find their soulmate.
🟢 A post-orgy group chat has become quite common, filled with pictures of orgy members holding one (or more) newborns, asking “okay, so whose is it?” It's not considered a very good/fun orgy if there's not a least a few people being fucked into, and through, their labor. A truly great orgy will be the cause of a local baby boom.
🟢 At a high school reunion, the former high school bully waddles over to their also pregnant former target to apologize for how they acted when they were younger. They have a deeply personal conversation about therapy and growth, only interrupted by a strong contraction and their waters breaking at the same time. As if to atone for their actions, the former bully ignores/ tries to delay their own birth in order to help their soulmate through their labor.
🟢 Someone who was pregnant with their soulmates baby for so long, they find they can't stand being empty once they've found their soulmate and given birth. Their reflection looks wrong, their body feels unbalanced, their entire sense of self is off. They demand/beg their soulmate to put another baby in them so they can feel like themselves again.
🟢 Enemies/rivals, startled and angry to find their belly dropping and contractions starting after they have a moment of realizing that maybe they have more in common than they thought. They immediately go back to fighting, which is difficult to do when their cramping bellies are sitting so very low on their hips, and their babies heads have rammed into their pelvis.
🟢 A sex worker whose appeal is that they don't want to know who their soulmate is. They host events and live streams, where they're blindfolded and the attendants are masked, and each of them take turns trying to fuck them into labor. While they have many fans, and many paying attendants, only one is the “lucky winner.” Their soulmate keeps fucking into them while they labor, giving everyone an extra show, as they remain blindfolded as they groan in pleasure and pain. Viewers are treated to the sight of them both crowning at once, the one blindfolded on their hands and knees, moaning about how they've never felt so full, baby in a full crown, driving their hips back to meet their masked soulmates cock in their ass, as they grip onto their hips for dear life and fervently thrust into them to distract from the burning pain they feel as their baby stretches them to their limit. When they take off the blindfold, they're met with the sight of their bruised hips, birthing fluids, two newborn babies crying, one with their umbilical cord leading back into them, the other's umbilical cord already cut, their soulmate already gone.
🟢 Someone who calculates their soulmates birthday down to the exact day, and will only date people with that exact birthday. After so long of trying they give up, eventually having a meaningless fling with someone else, falling in love with them despite knowing they're not their soulmate. They're both suddenly surprised when after a big conversation about feelings, they start to go into labor. Turns out their soulmate was adopted and didn't know their actual birthdate, but now they know their real birthday, and have their soulmate and new family to celebrate it with.