Not sure about the guy with Magnus. I thought Cerebro as well, but that's absolutely impossible. It looked like Magnus was looking at Grimlock on his screen, though I seriously doubt that was live feed--more likely Grimlock was a suspect for the shuttle theft. Looks like Berko will be showing back up, after all. Damned cool to see Magnus lose his temper the way he did, after seeing "by the books lawman" Magnus in the IDW-verse for so long.
Bad stuff has gone down on Nebulos, no doubt. Putting pieces together, it looks like there was a formal treaty between Cybertron and Nebulos to keep Transformers away. But part of it was restoring the Headmasters who lost partners in the Unicron War (and, presumably, the Battle of Klo). It specifically showed Brainstorm--fitting parallel that the first to undergo that experiment was the first to die fighting Unicron. (How I remember that, don't ask.) Someone has taken over Nebulos while the Autobots were away, and brainwashed the Nebulans. Bludgeon is a possibility. I'm thinking Scorponok, revived by the Nebulans (perhaps at the urging of Prime?), was really, really pissed at how "he" softened under Zarak's influence. The brainwashing could be a reverse-engineering of the binary bonding process, or maybe even the work of Mindwipe (also confirmed killed by Unicron).
From Grimlock's comments, something especially bad has happened with Slag.
Safe to say that Xaaron only called back the living Transformers in New Jersey way back when. After all, Grimlock and Thunderwing weren't returned, and I don't think Sky Lynx was, either. And, between the Decepticons in this issue and the stasis vaults when Grimlock "nucleoned them up," the dead (and near dead) weren't affected.
Megatron clearly found the dead Decepticons in stasis in Scorponok's former headquarters and revived them as zombies. Everyone in his group was killed during the Battle of the Underbase (all killed by Starscream except Ratbat, who Scorponok assassinated), and would've been in stasis there. Starscream and Ratchet are accounted for. So where are Galvatron and Shockwave? Obviously, he brought along only a small force, but it appears either he was especially confident or hasn't been able to restore the combination abilities of the special teams. Are the Constructicons among his lackeys? They've been MIA for a damned long time.
I'm going to guess that Josie never recovered.
Galvatron and Shockwave: MIA
Bludgeon: Leading an unknown group of 'Cons planning to overtake Cybertron.
Thunderwing: MIA, probably somehow preserved (at least consciously) by the power of the Dark Matrix
Demons: Unaccounted for. They could've been eradicated by the regeneration of Cybertron, but Primus seems to have been powerless before in dealing with them. Also, their origin has never been explained--were they forebears of the Transformers, or inhabitants of the planet before Primus became Cybertron?
Sky Lynx: MIA. Probably not with Berko, or it would've come up, but probably still in touch with him. I'm also thinking not on Cybertron, since a simple "Say hi to my big Pteranodon shuttle pal!" would've popped up in Berko's dialogue.
Mecannibals: Last seen eating all sorts in the Dead End. This was probably meant to explain why there seemed to be no
Soundwave: When did he leave Bludgeon's crew to return to Cybertron? And who came with him?
The big question to me, even though we never saw much of it: Klo. Nebulos and Earth both got screwed as a result of their involvement in the war. The Klozians were screwed over once by simply being in the wrong place. Unlikely Bludgeon would not be affected by a desire for vengeance upon them.
It'd be kinda fitting if Prime comes to Earth and defeats Megatron once and for all... by putting a bullet through Ratchet's head. I love Ratchet (who doesn't?), but none of this would've happened if he had executed Megatron back on the Ark when the two were merged.
I'm trying to think of any other wild cards. So far, looks like Furman's covering them all. I'd even forgotten about all the dead on the stupid island spaceship in Jersey.
