Nolan did tell him that he would give him training immediately, before the Viltrumites came, so I guess it was hinted at

So… they’re gonna make it harder for Mark to get the books now that they’re gonna get collected by the trash? Or does Art also have copies of those books stashed somewhere like in the comics?

no i know but he has the body (and i assume the brain) of what appears to be a ~40 year old man

Immortal being biologically and mentally like 40(?) being with Kate is very questionable, but even ignoring that, is that not a whole HR situation since he’s her superior? 😭