Another old one. This was written in October 2007, pre RotF, and assumes that Barricade was still skulking around on earth after the first movie.
Barricade was jolted out of recharge by the sound of two organic bodies impacting with his hood. This generally wouldn't have bothered him, except for the fact that he was pretty sure he hadn't actually been moving when he went offline. Which meant that the fleshbags had run into him.
Someone gasped. "This is a police car."
He recognized the voice instantly, despite the unfamiliar breathy tone of it.
"No one in it, is there?"
He recognized that voice, too, and it brought him out of his interrupted recharge as quickly as if it were the electronic signature of an approaching Autobot. Barricade brought his external sensors online just in time to see the human Mikaela Banes twisting around on his hood in order to peer into his alt-form driver's seat.
"No," she said.
Samuel Witwicky didn't respond, seemingly too involved in whatever he was doing with his mouth on her neck to be fully aware of his surroundings. Stupid organics. With situational awareness like that, it was no wonder their lifespans were so short.
Barricade cast his sensors about quickly. There were no other life forms in visual range. He could transform, grab the fleshbags- what in the pit were they doing? Whatever it was, their heart rates and temperatures had just jumped abruptly. Both were panting.
The female squirmed, rubbing her flimsy clothing and skin disgustingly against him. Barricade couldn't figure out why she was moving in such a fashion until he saw what the male's hands were doing. He'd picked up enough information on the biology of the human species to figure out what they were up to, and it was not going to happen on top of him.
The male put a hand down on Barricade's hood, apparently to steady himself. His skin had begun to seep moisture and the hand slipped a bit, smearing oils and smudges across his meticulous paintjob.
The humans stopped moving abruptly. The male lifted his head, leaning back when the female pushed at his shoulder so she could sit up enough to peer into Barricade's interior again.
He revved his engine and gave them something to see, holo-emitter flickering to life.
"Oh," said Witwicky. "Shit."