I just realized. One thing that Optimus will certainly be educated on by the Primes in the Haunted AU is the various was One Can Kill A Quintesson! Leaving some Autobots confused at times when he's teaching them in return because 'This sounds pretty Specific...???'
It's slightly competitive on the Primes' part because yeah, the Deceptions do got the High Guard being good at killing Quintessons too but. They're the Real Experts. (Are they salty? Naaaah they're not. Much. Kinda.)
AKJSHDK YEAH YOU'RE SO RIGHT I LOVE THAT <333
they got so good at squishing the goddamn bugs and they're thrilled they can save Optimus the pain of figuring out their weak points through trial and error like they did. they're gonna make a pro out of their baby brother in no time.
and if they just so happen to know some of the Decepticons will be majorly pissed off at the fact OP is already on par with the best of what used to be the High Guard when he only has a fraction of their experience... well, happy coincidences, y'know?
and if they happen to teach Optimus how to crack open a Quintesson in just the right way to make some Decepticons see ghosts through him... that's between them and the people they're haunting :)
haunted au