It's revealed in "Invincible" #76 that before he built the Coalition of Planets, Thaedus turned against the Viltrumite Empire, even managing to kill its then-leader, Emperor Argall, before fleeing the scene. Leaving the planet in chaos, he started anew, prepping for his former people to continue their mission across space and take over the joint.
While it's only briefly mentioned in the comics, this would make for a great standalone episode to really show how much of an absolute brute Thaedus was before he went all, "Hey guys, not cool!" to his own people. Besides that, it would also give much more time to a character that has the voice of Optimus Prime and, therefore, never outstays his welcome.
For now, though, all we can go is by the (comic) book and expect Thaedus to eventually cross paths with Mark now that Allen has put him on his radar. Given that the toughest line of defense is currently held up in a hospital bed, Thaedus will undoubtedly want to meet one of Earth's youngest protectors that could change the tide on the Viltrumite scourge. More importantly, if it hopefully does stick to the comics, he'll also be able to get his hands dirty once more alongside "Invincible" in the future. Trust us, you're about to hear Optimus Prime like you've never heard him before.
