A/N: This is a repost.
Megatron could only hope there was no-bot around to see this. This was the thought that ran like a mantra through his head as the dragon bit the back of his neck and pressed him down against the flight deck. Then Predaking growled, and Megatron felt the vibration deep, deep in his struts, in his tank, and his shame receded into a sea of lust. He bucked, his arms heaving as he tried to lift himself and failed. Predaking's tail lashed, and his wings spread and snapped with a sound like a clap of thunder. Predaking pressed him down again, but this time Megatron felt something rub against his aft. His claws gouged into the metal beneath him. On either side of him, Predaking's larger talons scored deep rents that put his scratches to shame. Megatron glanced at those claws - one swipe could tear him apart. The thought sent a full-body shiver rippling through his frame.
The dragon's breath was hot against the back of his neck. His frame pressed down against him, the heat of the flames within him making the planes of his armour burn against Megatron's. Megatron tried to find his voice to utter a command - he was the creature's master - but the tip of Predaking's spike butted against his aft and all words abruptly left him. He bared his teeth and gave a low, rough growl. His panels slid back. Predaking gave an answering rumble of pleasure. Megatron was panting, his optics a blazing, too-bright scarlet. He tried to struggle once more, because surely this was one indignity too far, he couldn't allow this, could he? Even if there was no-bot there to see, even if the dragon was sworn to him, even if this was setting all his systems alight...
Again, thought was forced from his head when the dragon moved. The broad tip of Predaking's spike rubbed insistently at Megatron's valve, and then, with a snarling grunt from the dragon, it found its way inside. Megatron gasped, and then gave a ragged shout. The dragon's spike pierced him and spread him wide, though only a small portion of its length had penetrated. Predaking's growl was a guttural, bass rumble. He didn't pause before drawing his hips back and thrusting once again. His spike sawed back and forth inside Megatron's stretched valve, and on each in-stroke Megatron was forced to take a fraction more of its length. He choked on his own intakes, he was panting, gasping, heat rolling off his frame. His claws scrabbled on the scratched metal beneath him and his feet slid and kicked. The rest of him was still pinioned by Predaking's weight, so all he could do was thrash and writhe as the dragon hammered its spike deeper and deeper. Megatron howled. Surely that was all of it, wasn't it? His valve felt stretched to breaking, and yet so wet, throbbing with heat rather than pain. At last, he felt Predaking ram the whole of his length inside him; he ground for a moment, rumblng in satisfaction, and then threw his head back and spat flame into the sky with an exultant roar. Megatron shuddered, on the verge of coming. Predaking resumed his grip on Megatron's neck, and the warlord found himself relaxing. Dark bliss pooled in his fuel tank. A dreamy look on his face, he pushed his hips up and back. The reaction from the dragon was instant - Predaking snarled and snapped his hips, sliding his spike back and then ramming it home once again. Megatron yelled, and Predaking repeated the motion, and again, until he set a punishing rhythm slamming into the warlord's over-stuffed valve. Megatron's shout was startled, and he came suddenly. His spike gushed transfluid and his valve tried to clench on the massive spike inside it. Predaking roared. Megatron thrashed, begging incoherently for more. The dragon forced another overload out of him within minutes, and several more before Predaking finally reached his own climax. When Predaking came, Megatron was boneless and languid beneath him and his valve was stretched and supple. Predaking snapped his wings open wide and drove his length deep into Megatron. His spike twitched, and Megatron felt the sudden hot gush of transfluid filling up his valve and overflowing his stretched lips, splashing and smearing his thighs and aft until he was nigh covered in the dragon's come.
He didn't move at once when Predaking withdrew. The dragon lingered a long time before pulling his spike out of Megatron's valve, and when he did there was an embarrassing moment as transfluid and lubricant poured from the abused opening and added to the puddle Megatron already lay in. The warlord hadn't the energy to try to stem the flow or cover himself. He lay where he was, his frame shivering as aftershocks crackled through him, moaning every now and then. Predaking stalked around him in a circle, his wings half open, his tail lashing. Then he curled around Megatron and lay down, keeping his master beneath the canopy of one wing, and within the protective circle of his body. The relaxed, prideful rumbling of his engines lulled Megatron, and his over-taxed system succumbed to the temptation of sleep.