BingLiu / BingLiuShen / BingQiu omegaverse AU based on this frankly hilarious idea here.
Liu Qingge is a cultivator who travels and fights all sorts of foes. He's also a character in PIDW. Because of this, he has a somewhat skewed view of sex (in relation to the real world), and treats things like heats as just something to get through in order to get back to the fight. Of course, with his tendency to travel so much his body is often under enough stress than his heats are short and infrequent. He does not keep track.
When that demonic disciple kidnaps Shen Qingqiu's body he of course goes to retrieve it, fighting Luo Binghe day after day after day without end. The fights are thrilling. Liu Qingge's omegan instincts *adore* Binghe, much as he tamps them down. The man has clearly shown his loyalty, fierceness and complete battlefield control. An *extremely* suitable mate. LQG does not give a fuck about this man, however. But when his heat sneaks up on him he's hardly going to stop trying to get Shen Qingqiu back because of a few hormones.
As great as these daily spars are for Binghe's excess of demonic energy, he's far from being *well*. Xin Mo still requires sating, ever more so in fact. But he isn't a heathen. Just because Liu-shishu is an omega (who can fight, who *does* fight him, snarling and vicious and bright and bold in a way that makes both his demonic instincts and his inner alpha sing) doesn't mean he wants to fuck him. He's saving himself for Shizun, and if shizun won't have him, no one will.
Unfortunately for both of them, they're in PIDW. And PIDW as a setting cares very, very little for what it's characters actually want. So LQG turns up on the cusp of heat. LBH fails to kill to sate Xin Mo for a little too long. They both recognise that the other risks serious injury/qi deviation if they put off their conditions, and as much as they hate each other for their tussle over SQQ, neither truly wants the other to suffer or die. So they dual cultivate to stymy LQG's heat, LBH manages to sate Xin Mo without triggering his own rut (desperately glad that that, at least, he's managed to save for Shizun), and they go their separate ways with a tacit acknowledgement that absolutely no one can know.
Of course, nothing goes the way we want things to go, and neither of these two people can be this casual about sex, at least not with each other. So it happens again. Regularly enough that even LQG recognises he probably should start actually using birth control. But there's no way he's visiting Mu Qingfang about it (how the hell does he explain he's sleeping with their sect's public enemy number one??) So he just visits a regular apothecary and is done with it.
Alas, the protagonist's spawn is a little too strong for some herbs to fight. LQG figures out he's pregnant a month or two before SQQ wakes up in the mushroom body, and everything is chaos for a while. Everyone is too busy trying to get to SQQ (himself included) to really do anything about this right now so he just doesn't tell anyone. Then BQ save the world (in their awful way), and go off and get married without anyone's approval before fucking off to the demon realm for a bit on their supposed honeymoon.
LQG is used to taking pretty much anything that happens to his body in stride so he pops out the kid (an extremely cute brat who, unfortunately, looks exactly like his father after only a few months) and continues his escapades travelling the world just with a baby in tow.
Sometime two years later Binghe finally mentions that he wasn't a virgin when he and Shen Qingqiu finally got together and SQQ responds "Well of course. You're the pro- I mean, Binghe is very attractive and had to deal with Xin Mo. This Master doesn't blame him. Besides, we weren't mates or even courting at the time." He asks no further questions, ostensibly because he expected it (he's seethingly jealous). Binghe very happily does not deign to mention it again.
They visit Cang Qiong for a few weeks on a whim and Shen Qingqiu takes the opportunity to finally catch up with his shidimei, calling in at Bai Zhan Peak. Only. What. Who. Why is there a small child attached to his leg. Why does that small child have a flame-shaped mark on his forehead and a mane of black curls??? LUO BINGHE WHEN YOU SAID YOU SLEPT WITH SOMEONE ELSE-
Tldr; Shen Yuan is extremely mad to find out that his husband is a deadbeat dad. Binghe I raised you better than this we are looking after our child from this moment onwards!!!
