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Chip is away on a task Sonic knows will take him a while, which is good. Because Sonic doesn’t want to hear anymore “why are you doing this, he’s your enemy, blah blah blah” than he already regularly gets from Amy.
And yeah, he’s still...getting used to this form. He altogether prefers his smaller, speeder self. But this form has some advantages, like the ability to pick Robotnik up, or to not have to jump up or bring Robotnik down to kiss him, though he still only comes up to the man’s chest. And despite how prickly Robotnik is, he’d made a smart comment about being the one to do this to Sonic and Sonic had growled, gravely and rumbling in his new voice, and Robotnik had suddenly resembled a tomato more than an egg.
And, okay, he should be angrier with his enemy, especially since the guy has gone a little extreme this time, tearing the world apart and all, but right now Sonic’s a little more concerned with trying to fuck Robotnik over the crashed pilot’s seat of the mech he’s just torn apart.
(And...alright, his other size was another nice new change to this body, he’ll admit that.)
Robotnik had sneered at his claws at first, but he’s not complaining anymore when Sonic digs them in to grip his sides harder, jutting his hips up against Robotnik’s ass as he thrusts roughly. Each one seems to drag a short, almost shocked noise out of the man under him, an odd reversal of how noisy Sonic prides himself on being. Which, he still is, but it’s igniting a flare in his chest to listen to his enemy make them too.
He’s getting close, the familiar tightening from his stomach to his balls, but he hasn’t exactly had an opportunity to explore this new body, and it feels a bit different even now. There’s a distinct feeling like something isn’t finished, like there’s more of his cock that’s trying to come out, and it feels like he’s on the right path of figuring it out by continuing to thrust into Robotnik. He probably should be more concerned, but he’s positive it’s going to work out alright. He distracts himself instead by licking up Robotnik’s spine, pressing a soft growl into the skin under his shoulder blades, letting him feel his longer, sharper fangs.
“You bite me,” Robotnik warns between grunts, “And I'll— ngh— rip those fangs out one by one.”
Sonic chuckles darkly, and dares a small nip, just barely pulling at the skin.
“S-Sonic!” Robotnik shouts, though he certainly doesn’t seem unhappy.
“I think somebody's into it.” Sonic says slyly, “Sure you don’t me to leave a nice mark on your neck? Or maybe your a—“
“Haah!” Robotnik says, though it sounds more like he’s trying to cover some other noise from his throat, “And let you rip— ohh— rip my throat out? No, I— ah— I’m not that swayed by your— ahh!— by you!”
Sonic chuckles, “Aww c’mon doc, what’s a few wounds between enemies?”
Before he can answer, Sonic grips him harder, shoving in sharply. It draws a high noise out of him, and Sonic smirks in victory when he sees the man’s arm that’s under him jerk itself faster.
Before Sonic can make a terribly clever draw between Little Red Riding Hood and Robotnik, there’s a slip in pressure between his legs, like whatever it is that’s been tapping at his primal brain is finally freed. It’s satisfying enough to not be bothered by that anymore, except now the base of his cock is bumping up against Robotnik’s ass rather than going in like the rest.
Robotnik makes a questioning noise, lifting his head slightly.
“What’s— what are you doing?”
“Uh.” Sonic says, though his thoughts are getting a bit foggy with still-growing arousal as he continues to thrust, “Di-Did my dick just get bigger?”
There’s some other weird new animalistic part of his brain that suddenly needs to push in as far as he can, that whispers unintelligibly it’ll feel so good, need to breed and Sonic’s a bit otherwise preoccupied or he’d take a moment to consider what the fuck those feelings meant. And really, Robotnik’s not complaining, not yet.
“I don’t think—“ the man starts to say, but it gets cut off with a moan as the base of Sonic’s cock pushes at his rim, and Sonic whines, digging his spiked shoes into the floor, trying to shove in. He groans when it’s not quite manageable, and takes back to thrusting faster.
His self-conscious mind grips harder on reality, enough to force out: “Uh— It alright, hngh, if I— y’know—”
Robotnik makes an angry grunt, but nods shortly, though it seems to bruise his ego to do it. Sonic grins, keeping the pace, still trying to work himself all the way in now. It’s a bit of work, but shortly enough he can feel something give, and Robotnik freezes up under him as Sonic tries again to thrust in.
“Oh— Wh-What— Sonic—” the man says with a sharp gasp, but shudders and moans all the same.
Sonic groans long and low, gritting his teeth and obeying the need to come, need to come, and the way his cock is finally going in and—
He feels the way Robotnik stretches around the larger base of his cock as he bottoms out fully, and Sonic’s orgasm punches through him, satisfaction arching down to his bones. An embarrassing howl makes it halfway out of Sonic’s throat before he silences it with a snap of his jaws, burying his nose into Robotnik’s back. Robotnik cries out too, and Sonic can feel him tremble and shift under him, and not for the first time they both sit in blissful peace in the afterglow.
Like always, though, it never lasts. Robotnik is the first to try and shift, but suddenly stops.
“What did you— get off!” Robotnik snaps, and tries to tug away.
Something at the base of Sonic’s cock sharply flares in pain, and they both make ugly noises.
“What the hell is that.” Robotnik grinds out, clenching his hands into fists.
Sonic, thankfully, is mostly coming back to clear-headedness, but there’s a large part of him alarmed that he’s still kind of coming, his hips still shaking with exertion (which is new) and his cock twitching snugly.
“Uh,” he says, because he doesn’t really know either. “Something...else changed with this body?”
“Get out.” Robotnik snarls, turning his head to glare at Sonic.
Sonic gently tries to pull away, but there’s that tug again and they both make high, strained noises. Sonic is trying his best to think, a small strand of panic rising up in him. He’s heard of something like this before, but the exact memory isn’t quite becoming clear.
“I think,” Sonic says, “We’re stuck.”
“What do you mean— Just…” Robotnik tries again, and gets the same level of success as before. He slumps a bit, breathing out sharply, then glowers back at Sonic again.
“You never said anything about this!” he says, and Sonic curls his muzzle.
“Well I didn’t know!” Sonic retorts, “I asked, and you nodded, so—”
“I thought you meant…” Robotnik blushes, just a bit, but then dismisses it with a snort and ruffling his mustache. “I never agreed to this.”
“Well you’re the one that made me like this!”
“Well I didn’t know it would do that to you!”
The dampening mood seems to be helping, but even with both of them continuing to try and pull away they can’t quite manage it without risking higher pain on both of them. Finally, Sonic relents to it, even if Robotnik is still grumpy, and the werehog slouches over the man, pushing him up against the chair.
“I am not a bed for you, you little pest.” Robotnik says, though his tone is less biting than his words seem to imply.
“What else do you suggest?” Sonic says with snappy irritation, “Happen to have a pack of cards or something?”
Robotnik makes a face of disgust at that, but lets the conversation lapse into silence. It’s the longest either of them have stuck around afterwards, pun not intended.
Sonic feels awkward now, for a variety of reasons, but eventually figures it’s only polite to say something.
“Look,” he finally offers, “I’m...sorry, alright? I didn’t know.”
“Well that’s no excuse.” Robotnik smarts back, “You certainly don’t see me shoving my fist up— up in you and then saying ‘sorry.’”
Sonic snarls, “I’m trying to be nice, here! You don’t have to be such a jerk!”
Robotnik scoffs. “If you wanted someone who was going to be sweet to you, why did you seek me out?”
The words seem to shock Robotnik just as much as Sonic, and the silence sits, thicker and uglier now.
Sonic stews on his next words carefully, or as much as he can since he’s no wordsmith like Amy is.
“Because,” he admits, a little softer, “I dunno. I’m having fun. Are you?”
It takes Robotnik an eerily long time to respond, long enough that Sonic can feel his body calming down, and it feels like it’s safer to try and pull out now.
“I hate you.” is all that Robotnik finally gets out, but he’s keeping his head turned away.
Sonic breaks out into a wide grin, his tail wagging enthusiastically.
“That’s it? Nothin’ else you got to say, Eggy?” he taunts, knowing he’s pushing it. Robotnik flushes, all the way down to his shoulders, and he whips his head around, an angry snarl across his mouth ready to snap back at Sonic.
“Hey Sonic!” a familiar voice calls out, and Chip zips up out of nowhere, “I got theee oh my gosh!”
Sonic and Robotnik both scream, and fall apart with a wet pop.
Chip vanishes off again, and Sonic’s left staring up at the brightening night sky turning to dawn. With a creaking of bones and a puff of fur, he’s suddenly back in his normal body.
“You.” Robotnik’s voice rings with rage and promises of violence, and as Sonic sits up he can see the man’s naked, shaking thighs, and the white globs of cum spilling out over them from where they just separated.
And. Alright. He’s gunna jack off to that later.
But for the moment, he gives his enemy a sheepish grin and makes his well-timed exit.