Okay, so Shiro thought that Keith had adjusted to the whole Galra thing pretty well. All in all, there weren’t too many physical changes he had to experience. Sure Keith had developed the fuzzy ears and his teeth were a little sharper and his eyes sometimes glowed with a yellow cast in certain lights but he had admitted to Shiro that at this point he was just glad he hadn’t sprouted a tail.
There were...other side effects of Keith’s Galra heritage that he had to learn to work around, though. For one, there was the matter of his dick. There’s no delicate way to say it: Keith was fucking hung now. He’d always had a pretty dick, though Shiro was biased, but along with the increase in size came a nodule that expanded during sex at the base of Keith’s cock to form a knot and wasn’t that an interesting situation. The first time he fucked Shiro after the development of his knot they were tied together for thirty minutes with his dick brushing along Shiro’s prostate every time he shifted his hips. He’d made Shiro delirious with overstimulation and once he’d gone down enough to slip out, Keith slid down between Shiro’s open thighs and eaten out his own come until Shiro was sobbing and pleading to be knotted again.
So yeah, that was probably the best part of all of this. Shiro was not ashamed to say that he absolutely loved to be railed repeatedly by his boyfriend. He loved it when Keith let go and embraced his wild nature and used Shiro’s body as he pleased.
Shiro knew he was going to get lucky tonight. He could tell by the irritated flicking of Keith’s ears that he was agitated and there were two things that were always guaranteed ways to ease his mind: sparring in the training ring and fucking Shiro silly.
They’d gone a couple of rounds in the ring with Shiro easily besting Keith because he was too wound up to make good tactical choices. Keith’s strikes were fast and a little sloppy and Shiro could easily read the pattern of his movements. Even in his frenzy, Keith was a skilled fighter and all he had needed to pin Shiro was one good opening. Shiro’s back slammed against the mat and Keith was straddling him instantly with his hands pinning Shiro’s wrists down above his head. He’d yielded, not caring to break the pin because the hungry look in Keith’s eyes made Shiro’s body flush red-hot and he wanted to let Keith take and take and take.
They’d stumbled to the showers where Keith promptly shoved Shiro into the wall of the shower and rimmed him until he came all over the tiles.
That’s one, Keith had murmured into his hip and it made Shiro shiver with anticipation. They wasted a few more minutes kissing and touching idly as Keith’s fingers crept down to probe at Shiro’s hole, tugging slightly on the rim until Shiro was hard again and pushing back against Keith’s teasing touch.
Once they were back in their bedroom, Keith pressed Shiro onto the bed on his back and immediately pushed two slicked up fingers inside him. He cried out at the stretch, hooking his hands behind his knees to pull his legs open wider. Keith added a third finger, glancing deliciously against his prostate and Shiro couldn’t help the moan he let out when Keith leaned down and took him into his mouth. Shiro didn’t bother to try to hold back when his second orgasm was barrelling down on him. Instead, he wove his fingers into Keith’s damp hair and bore his hips down onto Keith’s hand as he came into the wet heat of Keith’s mouth.
Shiro’s third orgasm found him on his front, face mashed into the mattress while Keith’s hips drove a punishing rhythm. His whole body was slick with sweat and his inner thighs were a mess of lube and cum and spit while his cock was dribbling a consistent stream of precum against his abdomen. Every nerve from the roots of his hair to the tips of his toes was aflame and oversensitized. He wasn’t speaking actual words anymore, only moans and cries that fell into the shape of Keith’s name.
Keith’s hands rubbed up and down his back, soothing and scorching in equal measures and he cooed out praises as he slowed his thrusts into deep, aching grinds.
You’re doing so great, baby, he whispered into the skin of Shiro’s back. Can you give me another?
Shiro had whined and nodded, knowing what was coming next and he even though his hole was sore and his cock was throbbing he wanted . Keith covered Shiro’s back with his whole body, pressing him down into the mattress and drove deep into Shiro. This position caused Shiro’s dick to drag against the bedding, making him whimper with sensitivity. He could feel himself getting hard again with every drag of Keith’s length inside him. Keith was mouthing and sucking along the line of his shoulder and neck, licking at the salt that was left on his skin. By the time he could feel Keith’s knot swelling against his hole he was fully hard again and already swaying dizzyingly on the edge. Suddenly with one forceful push of his hips, Keith’s knot popped his rim locking them together and Shiro was coming one final time. His pleasure swept through him so swiftly that it nearly hurt and he could feel Keith coming too, calling out Shiro’s name and pumping his hips as he flooded Shiro’s channel with his release.
When Shiro’s awareness refocused back on his surroundings, Keith had moved them so that he was spooned up behind him, still locked together by Keith’s knot. Keith was running his hands lightly along Shiro’s chest, fingers playing in the mess of cum on his stomach and letting his fingers brush along his nipples. Shiro arched slightly into the touch which caused him to pressed back into Keith’s hips making his cock graze against his prostate and he sobbed out Keith’s name because it was too much too much too much. Keith hooked his chin over Shiro’s shoulder and shushed his boyfriend soothingly, sweetly rubbing circles into his hip and telling him how good he was for Keith and how pretty he was and how Keith was so, so proud of him. He was sweaty and sore and his mind was absolutely blasted, but Shiro couldn’t think of a time when he’d been more sated.
He fell asleep like that, with Keith nestled inside him and whispering sweet nonsense into his ears.