A/N: There is slashy/adult content in this chapter. Don't like, don't read.
It was late when he finally finished with Sunstreaker—the fragging golden Pit-spawn was going to have to live with being ugly until he acquired a fresh coat of paint, but at least he would live—and Wheeljack and First Aid had long since finished with the other wounded, including Sideswipe, who had left his brother's side to be repaired only begrudgingly. The three of them were alone in the bay; Sides stared at him expectantly.
"He'll be fine," Ratchet said wearily, wiping energon-stained hands on a fresh cloth. "Let him get in a full recharge cycle and I'll clear him for light duty in the morning." He began putting his tools away, carefully cleaning them and his work surfaces as he did so. He missed entirely the flash of relief followed by a calculating look in Sideswipe's optics as he organized his set of laser scalpels.
He only looked up when a black hand laid gently over his own just as he laid the last tool in its proper place, and bit back a startled gasp at seeing the red twin's face so close to his own—and seeing such a fierce expression in his optics.
"Thank you," Sideswipe said in a low voice, then did the unthinkable.
He kissed him.
Ratchet stilled, CPU scrambling to come with the proper way to deal with this situation and drawing a blank.
Sideswipe was kissing him.
It was a not-altogether-unpleasant human custom, his fritzing processor decided, and began to kiss back.
A little niggling voice in the back of his head told him he would be sorry about this later, and it was so not fair to be pulling this slag on him when he was off-kilter from stress anyway. The rest of him told it to shut the frag up because it felt fragging good.
Sideswipe's version of seduction was a battering-ram against what was left of his logic functions, which were quickly overwhelmed by sheer sensation.
Primus, but his hands were everywhere.
How they ended up in his quarters, across the hall from the medbay, he wasn't quite sure. What he was sure of, however, is that somewhere along the way some part of him—the part that was currently in control of his motor functions—had decided 'to the Pit with it' and started giving as good as he got. After all, repeatedly piecing this slagger back together had to have its advantages; he knew both brothers inside and out, and was gratified to wring a breathy cry from the bigger mech just before they tripped over his 'charge pad and landed sprawled across it with the Lambo twin pinning the white 'Bot down.
Neither of them spoke; to have done so would have broken the tenuous web of desire that they both were wrapped in. The only sounds were the frantic cycling of vents as overworked cooling systems fought to keep core temperatures down, the quiet rasp of metal on metal from the motion of their bodies, and the various noises of pleasure that neither of them could refrain from making.
It was both an eternity and no time at all before Ratchet's world collapsed into a bright burst of pleasure when his systems reached critical status, and he was dimly aware of Sideswipe stiffening above him and emitting a low moan as he too achieved overload, energy snapping and crackling along all of their relays.
It was some time later when he felt Sunstreaker ease onto the 'charge pad with them and burrow into Ratchet's back, wrapping his arms and legs around them both.
Feeling incongruously, impossibly safe and contented, Ratchet lay in the dark and wondered just when he had lost his mind.