One thing that strikes me is that the Last Firstborn seems like he's the real deal of the sort of character the Impudent Tutor is pretending to be.
Both of them are wandering the lands — one leaving marks far and wide, the other deep — and both are seeking to spread knowledge for their own reasons.
The Last Firstborn is a walking font of Egyptomania, doing all he can to spread what remains of Nehekhara: it's gods, it's architecture, and it wouldn't surprise me if he was spreading it's art and it's culture in general at the same time. He's been largely bumbling his way through history by the read of it, but his effect on it seem at least as often positive as negative, especially with things like helping the Light College along under his belt. It does seem like he actually is trying to help even as he advances his own goals.
Meanwhile, the Impudent Tutor just really, really loves giving away deep dark secrets. If anything, he seems to be collecting even more secrets so he can give them away, if his students going into demonology as time goes by are any indication. His effect on things is more checkered, and while there's some bright spots, there's a lot of bleak ones. He's a total fake, with the twist that this conman actually can and even will teach you. It's just that rather than his knowledge or his history that's the lie, it's more his sense of morality that's a sham. If there's any truth to him in that at all, it's that he does seem genuinely fond of his students. He doesn't have a rotten thing to say about them even to save himself from exile, and the one bit that keeps even after he breaks character is reminiscing fondly about his Nefereta and Luthor.
The saddest thing is that I really want them both to win. But that is impossible.