Kevin didn't know the first thing about being a ghost. Unlike the Winchesters, he'd never been one before. But he was Kevin Tran, Advanced Placement – he could figure this out, no problem.
It took him a few days to work out how to navigate his way to the physical plane, and when he first managed it, appearing in the bunker's library, the sight he was met with would scar his dead soul for eternity.
He had always wondered if there was something going on with Dean and Castiel. He certainly didn't have to wonder anymore. He was standing right behind Dean's naked ass, bent over the back of an equally naked Castiel. And they were moving. And Castiel was making noises. Not very angelic noises at all.
If Kevin wasn't immaterial and consequently invisible, he's certain he would have flushed bright red.
He learned how to navigate away from the physical plane very quickly.
The next time he came to the bunker, he tried to make his appearance in a safe place: the kitchen.
Wrong again, Kevin Tran. Wrong again.
He threw himself through the closest wall, trying to block out the sound of Dean begging Castiel to fuck him harder. But his ears were non-existent, and he had no idea how ghosts controlled their hearing. Fuck, he could even hear them through the fucking wall. Where the hell was Sam? How did he deal with this?
It became a regular thing over the next several days as Kevin practiced appearing and disappearing. Kevin couldn't believe he hadn't caught them at it when he was still alive, considering how often they seemed to fuck. He learned to keep his eyes closed when he appeared and move quickly if he heard anything that sounded even remotely sexual.
Then he learned how to play with electrical currents and make the lights flicker. He was getting closer to making contact. He set the lights to flashing all down the halls of the bunker, hanging his immaterial head in his hands when he heard Dean's voice from a room nearby.
"Jesus, Cas. Don't think I've ever made you come that hard before."
"I'm not the cause of the flickering lights, Dean."
"Sure thing, Cas. Whatever you say."
Dean had rounded the corner not long after, walking right through Kevin, mumbling something about needing to brush his teeth after that one. Kevin shuddered at the thought, closing his eyes against the sight of Dean's disheveled hair.
It wasn't long after that Kevin figured out how to touch things. He took advantage of this new skill by banging around the bunker's kitchen. He couldn't believe the world's two greatest hunters couldn't spot a fucking haunting in their own home. What more did he need to do? He tried pushing the heavy wooden table, satisfied with the loud grinding noise it made as it slid across the floor.
"Would you two stop fucking in the kitchen!" Sam's voice yelled distantly. "I thought you agreed not to do that shit in communal rooms!"
Kevin hung his head in defeat. These men were impossible.