So, have you ever wondered what really happened after the Horus Heresy failed? Well fear not! For I possess a rare transcription of the alleged conversation that took place amongst the Traitor Legions as to what actions they should take after epically failing during the Siege of Terra. (The following is considered apocryphal and quite silly! I take no credit for creating this..only lucked out and stumbled upon it in some lost, dusty old Inquisitorial archive somewhere):
"Dude, Horus just croaked. What now?"
Abaddon re-tied his topknot. He totally had an idea. "I totally have an idea," he said. The Traitor Legions looked on expectantly. "Here's what we do. We run away."
Many helmed heads nodded. This seemed a wise course of action.
"Good idea," said Erebus.
'Hush." Abaddon frowned at the interruption. "But I think we should leave behind our jetbikes, Dreadclaws, Whirlwinds, Landspeeders - pretty much all anti-grav technology, really - as well as our bikes, attack bikes, and pretty much anything else we've used so far."
Fewer helms nodded this time. "Dude," said Lucius the Eternal, "we might need all that stuff. Some of that stuff is rad."
"Nah, I've made up my mind. Let's just go."
"Let's. Just. Go." Abaddon waved the Talon of Horus. Its scythe-blade fingers made clickety-click sounds.
"Okay, let's just go," agreed Lucius.
Kharn wasn't so easily placated. "What about Cyclone Launchers? Because I saw those in Horus Heresy: Collected Visions, so we must be using th--"
"I feel like I'm talking to myself, here." Abaddon pointed a claw at the World Eater. It poked Kharn in the eye.
"Ow, Jesus, man. Okay, okay. We'll go."
"Yeah, that's what I thought."
Abaddon pimp-walked from the room, strutting like he owned the place.
"Hey, what about this conversion beamer?" asked Typhus. "Couldn't we use these in Rogue Trader? These are awesome. They go, like, FWOOOOOSH."
"Leave it!" Abaddon's voice called from the other room. Typhus put it down, grumbling.