Interesting additions.
I think the necromantic doctor is way more powerful than any of the other agents. He can crush entire nations just by himself, while all of the other agents can do minor things to destabilize nations and such. It's quite easy to get an army of 200 or more undead for the necromantic doctor, which is a massive military force compared to how tough it is to get 200 for the Unholy Flesh.
Unfortunately I had a bunch of null-pointer exceptions that crashed the game. I think mostly they came from characters dying or their locations being destroyed. Once I used the Winter powers to lower temperature and it destroyed a bunch of cities, including the one where my enthralled was. For a while he and some of the others lived in a "ghost dimension" where they didn't exist but had their own society, before a null-pointer exception made an end of that. Likewise, I think when my Unholy Flesh or Undead smashed some cities, it caused problems(or maybe an agent that died in a war?). It's a bit hard to know where the problems come from, except that they're null-pointer exceptions that probably arise from a character disappearing, and then something referring to an empty state where the character used to be.
The limit of 2 agents and 1 enthralled feels so incredibly low to me. I feel constrained rather than being forced to make interesting decisions, honestly. Much of the time it's tough to advance in society or to influence it in any way(at least the way I play), so having just one enthralled doubles down on the feeling that it doesn't really matter all that much what I do in society.
Anyway, I think putting the vampire and the necromantic doctors as agents instead of Names is a good idea.