Summary: 6 pairings I could easier see than Renji/Tatsuki, and one pairing I couldn't.
Disclaimer: Kubo Tite's, not mine.
Notes: I do not in fact dislike Renji/Tatsuki. Perceived improbability has never meant dislike in my dictionary. :)
Pairings I could easier see than Renji/Tatsuki
Renji/Byakuya (or, Seppuku: the Two-Player Game for the New Millennium)
Renji wakes up naked in an unfamiliar bed with a headache like a troop of Menos Grande doing the cha cha on his forehead and a hole in his memory where he suspects he really, really doesn't want any recollection of last night to be -- but it's only when he sees his captain weighing his sword like he's deciding which of them he's going to ritually disembowel first that Renji realises just precisely how much trouble he's in.
Renji/Hinamori (shh, Kira is off having gay sex with Matsumoto)
Because Renji has these huge, bony hands -- not like her captain's, whose hands were beautifully shaped, refined, poet's hands -- Renji's hands are raw-boned, rough-skinned, but good hands, strong. They've never patted a frightened child on the head, or drawn a blanket over a sleeping girl. But they've never written lies, either: no elegant, heartwrenching letters of farewell; no knives in the back. Renji can hold a sword, and he can just about manage a heavy hand on a comrade's shoulder. And he never holds back out of pity, never goes easy on her because she's been hurt, like everyone else does, and Momo knows this is because you only held back with Kuchiki Rukia if you wanted a fist in the gut, but it's right, it's what she wants, this transferred ruthlessness. She doesn't want comfort anymore. She's going to stand on her own. Nobody's ever going to say about her, that it would be kinder for her to die than for her to lose, ever again.
So when Renji comes back from his wandering bleeding and drunk and triumphant, Momo forces him down and goes over every cut with antiseptic, ignoring him when he curses at the sting. It's too much kindness: she doesn't need to be told that he still wants it to be a punch in the face and a string of expletives. But she does the best she can, and he thanks her gruffly when she's done. They'll never be enough for each other, but that's okay, kind of.
Renji/Ichigo (because two shounen blockheads are always better than one)
"So what is it you're compensating for with that fucking huge zanpakutou, anyway?"
Ichigo shoved his knee in Renji's chest and smirked. "You want to find out?"
Renji/Yuzu (It's Sgt. Pepper's Lonely Hearts' Club Band! I hope you all enjoy the show.)
"Sometimes I'm a little jealous," Yuzu confessed, watching wistfully as Rukia got Ichigo in the right eye with a coffee table. "Rukia-chan is great, but ... you feel a little left-out, when somebody you love gets along so well with somebody else."
Renji looked away. "Huh."
Renji/Kira (Hinamori's off, um. eating watermelons with Hitsugaya?)
Years of friendship and associated violence had yet to accustom Kira to Abarai Renji's idea of hello. Since this frequently involved the application of a blunt object to the back of the head, Kira felt he could be excused.
"Stop moping about Ichimaru," said Renji. "He was an asshole anyway. Never got what you saw in him. Aizen-sa -- Aizen, yeah, okay, but Ichimaru?" He snorted.
"You're not very good at this, Abarai-kun."
"I look like the fourth divison to you? I'm just sick of you fucking drooping all over the place. Get over it. So he was a dickhead, at least he's gone."
The words came almost against Kira's will, riding the cresting wave of annoyance:
"And what's left is better?"
Renji paused at the door and looked over his shoulder, gleam of his eyes like the light off a blade.
"Give it a try," he said. "You never know."
Renji/Rukia (rosa rubicundior, lilio candidior)
One pairing I couldn't easier see than Renji/Tatsuki
Renji/Urahara (voulez vous couchez avec -- you know what, never mind.)
"Fuck you, asshole!"
"Only if you ask nicely. ♥"