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Optimus threw back his helm and groaned as he rode the thick spike sheathed inside him.
“Will you listen to me now?”
Grimlock’s servos left marks as they clawed the desk under him, trying not to grip Optimus’ narrow hips. He shook his helm and glared up with dim optics.
“Me Grimlock won’t listen to you Prime. Never will.”
The tight valve engulfing Grimlock’s spike lifted until only the head was left inside, it then halted, refusing to slide back down. Grimlock rumbled deep in his chassis and reached to grab Optimus, to make him go back down. Optimus moved fast, pinning Grimlock’s wrists to the desk and slid down until Grimlock’s spike was once more fully seated inside him.
“You don’t decide what happens here,” the prime purred into Grimlock’s audial. “If you try to take control I’ll leave you here, aching and wanting. Though there is one way for you to have control, you know how.”
“Me Grimlock strong! Can just take without giving back.”
“Really?” Optimus raised an optical ridge in question, calling Grimlock on his bluff.
Grimlock was glad his faceplate was still in place, hiding his expression from Optimus. Of course he would never force a berth partner, he may not be the nicest of mechs, but Grimlock still had a code of honour. He still didn’t want to submit to the Prime though.
When Optimus had ordered Grimlock to his office he had thought he’d known what he was in for. A harsh rant from Optimus, about how Grimlock had refused to follow his orders in battle once again, instead chasing stragglers while the rest of the Autobots had been left to fight the Decepticons.
Afterwards he’d expected to have several privileges taken away or at worse a day in the brig, to think about what he’d done. Grimlock had been shocked when the yelling match had turned into Optimus riding him on the thankfully sturdy desk.
He didn’t want to bend to another’s will, to stand in line like every other Autobot. But the way that valve rippled around him was just too much, far too good. His body went slack and he sighed, glaring up at the expectant Prime.
“Fine! But me Grimlock get to decide everything that happens when we frag!”
Optimus’ head tilted and Grimlock swore he could see the smug smile hidden behind that silver mask.
“Deal.”
Grimlock’s spark sunk, he felt like he’d just sold himself for a cheap frag. But if he was going to sell himself, might as well make it worth every second.
He roared and flipped Optimus so his back was pressed flush against the desk. He leant in close until their masks were almost touching and inhaled deeply, capturing Optimus’ scent, old data pads and cheap energon.
“Me Grimlock may be yours, but you Prime are mine.”
He gripped he edge of the desk and set a furious and punishing pace, driving his spike into Optimus’ valve without restraint. In return Optimus hooked his legs round Grimlock’s waist and wrapped his arms round his neck, clinging on for dear life as he fragged into the desk.
It was glorious, everything Grimlock could ever want, from the fluttering valve to the harsh moans of pleasure in his audial. He didn’t last long, not enough to make Optimus overload as well, but it didn’t matter. He was new to interfacing and he would have plenty of time to learn.
He looked down at the exhausted Prime on the desk, cooling fans set to max and valve leaking silver transfluid. He spread those shapely thighs and retracted his faceplate. Oh yes, Grimlock was going to enjoy this and he was going to make it worth his loyalty.