Human and Viltrumite genes are incredibly similar, which is why Mark can go head-to-head with a Viltrum native, in theory.

Invincible is getting ready for a brand new story in Season 4 not seen in the original comics, and this could be the perfect ...

and there are even a few that seem to have united with the Viltrum Empire completely. But thankfully the Mark we have been following all this time hasn’t gone down one of these destructive paths ...

Conquest confronts Mark and discusses with him his progress ... more about fighting than the assimilation of planets for the Viltrum Empire’s expansion. He then begins his fight with Invincible.