I never read the comics, so my only impressions of him were from Season 1. Even in Season 1 not much was disclosed about him, but the dude is Abraham Lincoln. I always thought of him as being wise, amiable and good natured. Now he just kind of seems like an asshole, and that whole hooking up with Kate thing definitely brought his moral code down a few pegs in my eyes. I can’t blame his misgivings about Invincible, but why is he a jerk to everyone else? Maybe you just stop caring after a couple millennia.
We go through an entire season, but for Immortal it has been a month(maybe less than that depending on how long it took for Cecil’s team to revive him) since his team, his friends (it also seems like he had a special thing with War Woman, her “i chose us” sounded like there was something more), got brutally murdered by “someone close”(in his case twice).
So yeah, he’s grumpy at the “inferior replacements” he’s now in command, it’s understandable him feeling disconnected to them, that he needs to be harsh on them and teach them what “real hero work” is like.
Can’t speak much for his thing with Kate, it looks morally wrong and that he’s taking advantage of a young girl(everyone is young for him though), but we don’t know how it began. It may have been started by her even and in his vulnerable coping state he went for it, in the comics it apparently blossoms into a nice relationship so i’m trying not to judge.