Notes and Disclaimer: This is a crossover with Sandman, and it does assume basic familiarity with the Endless. A number of pairings (both het and yaoi) are implied, but the focus is the Yumichika-Ikkaku friendship.
Bleach is the property of Kubo Tite, and Sandman is the property of Neil Gaiman. This was written solely for entertainment (and to get this plot bunny out of my head) and not for profit.
To be honest, there were times when Yumichika kind of freaked him out. For a long time, it wasn't something Ikkaku could easily explain, not even to himself. Yeah, he knew Yumichika was keeping some sort of secret about his shikai--which kinda frosted him, since he'd told Yumichika all about his bankai--but that wasn't it. The guy had been his best friend for years, but there had always been something there that wasn't quite...
...well, something about Yumi didn't always sit right with him, and damned if he knew why.
For a while, he wondered if it may have been that there were times when, if Ikkaku hadn't known him, he wouldn't have been able to guess if Yumi was a guy or a girl. In fact, there were times when Ikkaku had to remind himself that yeah, he'd seen Yumi naked, and yeah, he was definitely a guy. But then again, sometimes he'd look at Yumi his mind would pick up all the cues and would start cooking up vivid memories of tits that weren't really there. Five minutes later, though, Yumi would move in a certain way, or his eyes would narrow, and Ikkaku would wonder why the hell anyone could ever mistake him for a girl. Yeah, it was really fucking strange, but it didn't bug him. It was just something he'd noticed over the years.
Later, he thought it probably had something to do with the fact that Yumichika was so damned beautiful that even men Ikkaku knew were straight would take a second or even a third look as Yumichika walked by. Hell, he'd even caught Zaraki giving the guy a considering look once or twice before covering the slip with bluster and an order to do another twenty sets of drills.
Ikkaku thought maybe he should be worried about the kind of rumors that would go around about him for hanging out with such a gorgeous guy. But he just wasn't worried, not even when he tried to make himself be. Not only did the idea simply seem completely fucking ridiculous, he never heard a single hint of even the tiniest rumor about him and Yumi, even when Ikkaku had passed out drunk with his head on Yumi's lap. On the other hand, all it took was for Renji to say hello to Yumi just a little too friendly-like, and the next day half the Gotei 13 was saying they heard the two of them were banging like bunnies. Strange.
But then one day, Ikkaku watched--really, truly watched--how Yumichika turned his attention on an attractive new recruit (funny, how those gray eyes could look almost amber when Yumi was in the right light and the right mood) and the young shinigami had instantly become enraptured. Gray eyes glinted gold, and while the mark was utterly entranced, Ikkaku shivered because he saw something like the glint of a knife in Yumi's smile.
Now that he'd noticed it would see that smile again, over and over throughout the years. He would see more people fall to that sharp, perfect smile. Iba. Kotetsu. Hisagi. Dozens of others. Men and women. Anyone Yumi decided he wanted. All his little 'favorites.' And Ikkaku had no doubt that he, too, would fall if Yumichika wanted him to.
But he never did. Ikkaku could sling an arm across Yumi's shoulders, and there was nothing more to it than companionship. He'd seen Yumichika naked before (and vice versa) more times than he could count, especially when they were living rough and on the run, and there was never any hint of interest, no blood rushing to the head, no twitch in his cock, no embarrassing dreams, nothing. They'd even slept tangled up together against the cold or because there was only one futon for them to share, but nothing ever happened besides sleep and stolen blankets. He just wasn't tempted, and he didn't know why. (But once, when Yumichika had done nothing more but smile and nod at Hisagi in passing, Ikkaku would have bet a week's wages that Hisagi was about to take Yumi then and there in the middle of the bar, right in front of everyone.)
"Why is it you can get all these people? Hell, when you're really working it, you got more people panting after you than you know what to do with" Ikkaku finally asked, bitter and frustrated after a long dry spell in the sex department. "And why the hell ain't I ever been interested? Not that I'm complaining, mind you. It's just, well..." he shrugged. "It's something I've wondered about, is all."
"Let's just say it runs in the family," Yumi said, turning that devastating smile on Ikkaku for just a second. And even though it was the middle of winter, there was the barely perceptable scent of summer and peaches. "Blood will out, they say, even after death. Perhaps especially after death," he said a little sadly as both smile and scent faded, "but you're the best friend I've ever had, and I don't want that to change, so let's leave things as they are."
Ikkaku nodded. "Sure. I can live with that."
And so he did.