i mean unnus annus is basically the series he had with ethan and tyler on his channel, markiplier makes, except it had the theme of death. tyler didn't join because his mom had just died and he didn't want to spend a whole year making death themed videos.
mark 100% has an ego issue, which he seems to be aware of. there was some video of the early covid days, when they were in their offices each, facetiming each other, and mark admits he's egocentric(i think he might've used self centered, but same thing).
i never liked the whole bit of him talking down on ethan. i don't understand how he ever thought that's funny. literally acting like your friend is beneath you and that you're much better than them. it's fine if it's a one time joke, but it was basically any time they were doing any type of competition type video, mark would start it. like the stereotypical mean girl that always talks down to her friends