My two favorite sins combined

Knock Out knew exactly what he was getting himself into before he had even stepped foot inside of Starscream’s quarters after the comm call requesting his assistance. It happened all the time, almost on a schedule, and lately, Starscream had been due for another needy night after the long, stressful span of time he had suffered through.

Today was particularly difficult on the poor mech as Knock Out had been told, but without any helpful information gathered from his best source—Starscream himself, of course—he couldn’t be sure what was and wasn’t going to be asked of him. He could guess, however, just as he had guessed every time before whenever Starscream was feeling moody after a day full of heavy duties and demanding his assistance, so Knock Out did what he did best… and he prepared everything.

He brushed off Breakdown’s confused stares as he collected the last bit of edible rations given to the medical bay to use, and he ignored the assisting Vehicons’ curious questions whenever he rummaged through his secure bag of not-so-common medical supplies before gearing up and taking his leave for the night. It didn’t take a long-winded explanation for Breakdown to know exactly what was going on by that point, and by the time Knock Out had made it to Starscream’s door, he was already getting a separate message from his fellow medibay staff.

Go easy on him, doc, Breakdown wrote. I’ll be here as backup if you two need me.

“Oh, Breakdown,” Knock Out sighed with an amused smile. “Surely you should know by now… this won’t ever be that kind of visit.”

No, it was never a medical visit when Starscream called him and only him up to the second’s private quarters, and as far as Knock Out was aware, it never would be.

It was always the same deal—Starscream, pitiful and needy, lying curled up on his side in the center of his berth and glaring at the door while Knock Out let himself in. Today was no different, and Knock Out allowed himself a little huff of laughter to go with his smile as he watched Starscream uncurl himself just enough to watch his medic more closely.

“Starscream,” Knock Out greeted simply, cocking a hip and propping a servo on it as he let his bags drop to the floor. “You rang?”

Starscream barely moved another inch. He grunted in return, his optics drifting from Knock Out’s face to the bags he’d brought sitting by his pedes in front of the door.

“So,” he finally drawled out after a long, dramatic pause, “you already seem to be aware of what I’ve asked you here for. Always prepared, aren’t you, Knock Out?”

“When the situation involves you?” Knock Out tilted his helm. “Indeed I am.”

Starscream fell silent again, clearly thinking. Then, with a sigh as dramatic as his quiet, he unwrapped himself fully and scooted up to the top of the berth.

“Come inside, then,” he grumbled. “No point in wasting any more time.”

“Ooh, someone’s awfully testy,” Knock Out said back as he swooped down to snatch up his bags again and moved to join Starscream on the berth. He tossed them into the center before crawling onto the edge, settling for sitting there with his feet dangling over the ground as he studied Starscream more closely. “What happened this time? Was it Megatron? The Autobots?”

“Everything!” Starscream huffed as he slumped forward, his arms crossing over his chest. “Everything that could have gone wrong went wrong, and of course I am the one to blame for it.” He rolled his optics, deflating even further. “It seems to be Megatron’s favorite pastime, resigning me to carrying all of his faults. What does it matter if I am the second in command when there are so many other burdens to carry for him?”

“Ah.” Knock Out’s expression softened with sympathy. “A rather bad day then, hmm?”

“Very much so,” Starscream said, his stony expression remaining solid… until it didn’t. He softened up, too, his optics suddenly pleading. “Which is why I called you in here tonight. You always were good at the whole… well, you know.”

“Feeding and fragging?” Knock Out asked. “It’s what I’ve come prepared for tonight, if that’s what you’re looking for.”

That was all it ever took. The fight left Starscream in an instant, and like all of the times he had before, he looked weak and vulnerable under Knock Out’s gaze as he nodded and frowned.

“Please,” he said, desperate and needy.

Starscream didn’t need to beg twice. Knock Out was already reaching into his bag for the first set of cubes with a wide grin on his face and a dark, sultry glint to his optics.

“Consider it done, Starscream,” he said. “The doctor is in… and he’ll be staying for the duration of your care.”

Care of which involved being stuffed until he couldn’t move and then being fragged into a senseless pile of babbling words and pliant limbs that lay limp atop the berth’s sheets. It wasn’t the typical treatment plan, but for special patients like Starscream, Knock Out was more than happy to make an exception.

Knock Out was tender as he pulled cubes of medical grade out of his bag and fed them to Starscream. He held each one by the bottom and pushed the corners up to Starscream’s lips, forcing Starscream to drink it all down without stopping. It was the perfect kind of helplessness he needed to get his commander out of that addled processor and into the moment, and with each cube Knock Out stuffed down Starscream’s throat, Starscream became more and more relaxed and compliant.

There was plenty of energon to fill up Starscream’s belly with and more, and Knock Out made sure to use up every last bit of the stock he had brought in. Starscream was well past speaking coherent words and phrases by the time he’d maxed out on his tank’s capacity, and once Knock Out had fished out the last cube in his bag, Starscream was no more than a hot, panting mess of swollen mesh and frantic fingers that worked against the curvature and desperately fought to quell the pain from the built up pressure inside.

“Easy, commander,” Knock Out purred as he set the last empty cube aside, his fingers already moving towards Starscream’s stuffed middle. “Just relax… let me help you feel better.”

At that point, Starscream didn’t protest. Primus, he didn’t even move—couldn’t even move. He was nothing more than a whimpering, squirming mess atop his berth as Knock Out straddled his lap and worked skilled fingers into the creases of his plating to release his big belly from its containment. Starscream sighed in relief as the excess plating was lifted, and he groaned as Knock Out worked deeper into the taut mesh, the tips of his claws tracing teasing circles as he went lower and lower down Starscream’s frame.

“Ngh… Knock Out,” Starscream gasped, just barely managing to lift his helm up and meet Knock Out’s gaze. His frame was hot, his vents pooling out steam, and he trembled under every new touch of Knock Out’s fingers against his mesh. “Knock Out, please…”

“What is it?” Knock Out purred, his fingers playing with the creases between the plating on Starscream’s thighs. He spread Starscream’s legs apart a little further, exposing the array beneath. “Haven’t you had enough of me yet?”

Starscream’s mind was mush, and his belly kept him pinned in place. There was nothing he could do himself to demand what he wanted next, but Knock Out knew. Oh, Primus, he knew.

“Open up,” Knock Out said, a claw tapping against the panel sealing away Starscream’s valve. “Let me finish your treatment.”

There was a hiss as pressure released, then a sigh as Starscream felt Knock Out’s fingers tracing the rim of his valve. He was slick and sticky already, his desperation having grown during Knock Out’s feeding.

When he finally felt the tip of Knock Out’s spike slotting inside of him, he whined, his fingers clawing at the sheets and his helm thrown back against the berth as Knock Out slowly filled him up. He was already out of his mind, his stuffed belly leaving his helm buzzing and his charge burning. By the time Knock Out was done with him, he knew he wouldn’t be able to think, let alone speak.

He was so, so full, and he felt so, so good. He couldn’t move anymore—not at this size, not when he was this full—but he knew he didn’t need to. Knock Out would take care of him…

The guy becomes a UNIT. RIP to anyone that even tries to mess with him