Slimer in the Machine

"Blast it!" Galvatron screamed into the empty air, "WHY can't you leave me ALONE???!!!"
"I'll NEVER leave you alone," the all-too-familiar high-pitched voice taunted him, "NOT until I get back what is rightfully mine. How ironic that by destroying me, you ensured that I would be a thorn in your side for all eternity!!! Ah, hahahahaha!"

'"STAAAAAAAAAAARRRRRRRRRSCREEEEEEEEEAM!!!!!"

—Galvatron and Starscream

Slimer In The Machine is a Crossover fanfic written by Sheba. Set in Season 3 of Transformers Generation 1, taking place after the episode Ghost in the Machine, it starts with Galvatron being plagued by Starscream's Ghost. Earth-savvy Combaticon Swindle suggests that Galvatron hire The Real Ghostbusters to dispose of his nemesis.

Tropes used in Slimer in the Machine include:

And I Must Scream: Galvatron, when faced with the possibility that he'll be haunted by Starscream forever.
Ax Crazy: Galvatron.
Canon Discontinuity: While Starscream's fate in the G1 episode Ghost In The Machine is not explicitly specified in later episodes, and it's highly suggested that he's the victim of a Bus Crash, he does reappear in commercials as a Pretender.
Covered in Gunge: Well, it does have Slimer in it.
Demonic Possession
Nice Job Breaking It, Villain: Galvatron shoots the trap that Starscream's being held in.
Our Ghosts Are Different
Shout-Out: The title is a reference to the name of the episode from which it was derived, which itself is a nod to this trope.