Twins First, Lovers Later
Sakon knew things about Ukon that nobody else knew. Like how he had a scar across his inner thigh that looked a bit like a scorpion on steroids, and how he always hissed when he got touched in this one place behind his ear. Sakon wasn't sure when he started knowing about those things, so it was debatable whether it was through their bedtime activities or through their dysfunctional family relationship.
They were twins first, lovers later. Neither of them knew when it had started, only that Sakon remembered them coming home from a mission and not being surprised when Ukon had poked his hands out and snaked them down into his pants.
There were certain things that people would say were wrong about their relationship, of course. The foremost being that they were twins, and the second being that they were both male. But Sakon and Ukon had never exactly been raised in a stable and loving family, so they didn't know much about how normal relationships were actually supposed to work. And even if they did, it was unlikely they would care.
Coming out of the closet had been hard, though inevitable. The first person they went to was Jiroubo, thinking he'd mind the least. Rather, he'd stared at them for half an hour and left to wash his hands and face after being sworn to secrecy.
It was two years before the twins decided to tell Kidoumaru, wondering if he'd react any better. He laughed so hard he snorted a plum up his nose, and while busily picking at it with one of his arms, used he other three for balance as he reeled back, realizing it wasn't a joke.
They never told Tayuya. She asked about the increased tension between the male members of the Sound Four in her own usual way(What the fuck is the matter with you little shits?), but none of them answered.
Surprisingly, the most accepting of the Sound Five was Kimimaro, who somehow managed to find out. He simply walked up to them and said 'Congratulations.' It was the first time anyone had seen him acting in any way other than like an asshole without being near Orochimaru, but Ukon figured it was just because Kidoumaru finally managed to sneak those hallucinogens into his soup at dinner like he said he would.
Kabuto weaseled it out of Kimimaro, and he just laughed and said that if they ever wanted a child, he'd have a surgical table ready.
They were lovers, but they were twins first, so gradually they were accepted again. Kidoumaru figured that since they'd never exactly acted like they were gay and lovestruck, they'd be all right as long as they kept clean on overnight missions, Jiroubo forgot about it when Tayuya tricked him into smoking a whole cigar, and even if Kimimaro cared, he wasn't on missions enough anyway for him to matter.
Sometimes Kidoumaru asked him why they'd never found a woman, or why they'd never found another man(sexuality was a very loose thing in Otogakure). Ukon responded that nobody would ever make him gasp like Sakon. Jiroubo asked why they started dicking each other in a rare fit of profanity, and Sakon replied that Ukon was the only one he'd ever bend over for.
That still didn't satisfy their two comrades, but it kept them satisfied, and they never asked about it again.
When the Sound Four were dispatched to bring Uchiha Sasuke, Sakon and Ukon wanted one more night, in case they didn't make it back from Konoha. Kabuto said no, on account of, 'making it more satisfying when you get back..' Ukon would've jumped him, but Kabuto was the one who first introduced a non-painful way of doing anal, so he figured he'd wait until next time.
Then that dog-brat came along, and for the first time, the twins were actually afraid. Then they nearly killed him, and Sakon thought of a new position that involved rope and ball-gags, and then that Sand-nin arrived, and everything fell apart.
When Sakon fell back into the puppet, Ukon didn't stay in there because he couldn't have left. They were twins, and they were lovers, and both of those always went with the other, and they couldn't have lived without each other anyway, or so Kabuto had said when he mocked them for the 25th time after getting back from Konoha.
Besides, Ukon figured, Sakon could reward him with a couple days when they found each other in Hell. He was big on that kind of self-sacrifical stuff.
BWAHAHAHAHAHAHAHAHAHHAHAHAHAHAHAHAHA.
An incestuous and gay pairing I actually think would work, yesss. I'm actually getting more 'warmly indifferent' to shounen-ai/yaoi stories rather than 'mildly disapproving.'