So here's Guiltaur! My awkward nervous laddo!
(He's actually a CANON character if you can believe it!, Yes an actual Megs/OP 'hybrid'! Their name is Gilthor, but they were called Guiltaur for a while due to a translation error, but I'm still sticking to that name for this "OC-ification")

Bio:
Guiltaur was a hybridised experiment created by the Quintessons.
They had an inside bot cut Cybertron off from contacting any external help and sent this baby down with an army.
He worked well, bulky and outfitted with heavy weaponry the guy was a formidable foe on his own but one thing he wasn't prepared for was reclaiming the Matrix.

The Quintessons found themselves missing a weapon and an army down.
The Autobots found themselves up a child.

Guiltaur was, if anything, a 'child' drugged into sleeping so his Spark could be used as a power source.
Optimus, despite Ultra Magnus's protest, felt pity for the child and well... he IS at least 50% Optimus, so... it makes sense?
Optimus promptly adopted Guiltaur and made him his official 'son', vowing to shower the child with all the love he could ever want.

Personality:
This guy could well be the definition of insecurity. Easily riled by anyone challenging his authority, easily coming off a little arrogant as he will get confrontational with those who pick at him too much in an attempt to 'assert himself' and prove he's a capable leader.
He really wants to try his best and not disappoint anyone but it’s hard when you doubt yourself. I mean it's also not helped when he so obviously shares coding with the most reviled being in the galaxy. As such he desperately does his best to shrink away from the spotlight, which puts him at odd with the part of himself that wants to show off how great and trustworthy he actually is.
However, there is some more to him beneath that but it's rarely seen.
Guiltaur has a paralysing fear of guns and cannot bear to touch them as such he takes lessons on melee combat.

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