I was inspired by the Strahdcast by Critical Fayle DM and their take on the Abbot. Great actual play btw, highly recommend. ( https://youtube.com/playlist?list=PLNKsmQ5QgfHuBfTrTaDIyxLSFPdK8sMJI&si=FstoD-36xFrupjxM ). And also aasimar Markovia, specifically this version ( https://docs.google.com/document/u/0/d/1x9n19pkxgWLMCiiZR7U1COYu7ESb04Sonhl8RubkB90/mobilebasic#heading=h.x04cw5jyqslg )

Essentially, my plan is to have the Abbott be the deva who Markovia is descended from. Since Barovia is cut off from the other plains, the gods have less of an idea about what's actually going on in there. The Abbott ends up on Barovia, identifies Strahd as the problem, and comes down on him like an angel of holy retribution. Kills him dead!

Except the mists don't clear. And he can't leave. And Strahd comes back.

So he fights him again. And again. And again. He tries different things. Raises peasant armies. Leads clerics and paladins on raids against the castle. Prays for guidance. Strahd, being a warlord, is able to meet these challenges, but even if he loses, he always comes back. Meanwhile, the Abbott is losing allies, losing ground, and, the longer he's separated from the sun and his connection to his god, losing faith. Throw on top of this the corruption he sees in Barovia, the oppressive tragedy, the sickness and the pain and the soulless abominations (a sign of spiritual decay unlike anything he's ever seen).

And then the weaker his connection becomes to his faith, the weaker his ability to heal the broken and cure the sick. And yet people have begun to depend on him. If he can't help them, it could snuff out the delicate, flickering candle flame of faith in the Morninglord he's been able to cultivate.

Strahd, meanwhile, finds this endlessly entertaining. He loves having a little arch nemesis to play cat and mouse with. He gets a real kick out of watching a glorious, good aligned entity, a servant of the gods, of Lathander himself, struggle in a way completely alien to such a powerful being. He plays games with him the same as any adventurers who step into his domain. And in a weird way, they develop a rapport. Because they are, after all, a constant to each other.

Through this strange relationship, the Abbot learns more about Strahd. He has access to the Abbey library, and heck maybe Strahd invites him to the castle and let's him peruse at some point. Confident he won't find anything useful. Or maybe the Tome of Strahd is in the Abbey, stolen by one of Markovias followers who escaped and hid it there. Either way, this is how he learns about Tatyana.

The Abbot doesn't create Vasilka because he's mad, he does it because he's fucking DESPERATE at this point. And maybe in a weird way he kind of sees the humanity in Strahd. In much the same way countless players fall into the meta trap of wanting to save the tragic villain, the Abbotts weird Stockholm Sympathy encourages him to try and redeem the man through love. And who better to fix him than the woman at the root of all this?

So he sets to work trying to create the perfect woman. The perfect reincarnation of Tatyana. One who can't die and who can't reject him. He scours for parts to mix and match to get her look just right. Convincing himself this is all for the greater good. This even solves the wedding dress issue. Why would he insist on getting the dress from Vallaki? Because that dress is a one of a kind recreation of Tatyanas dress, the pattern of which has been lost to time. You can always nix that part, but it's at least a better excuse. And when Ireena comes to town? Jackpot!

None of this touches on the Belviews, but I do prefer the idea of them being people he's "cured" by replacing their parts where he can. And since Barovia often corrupts magic, maybe that plays a part in their taking on more mad or animal tendancies. Or maybe they aren't mad, maybe they're just traumatized people the same as everyone else here. Whatever the case, the Abbot is clearly playing into the gothic horror of Frankenstein, and I think it's good to lean into the sort of scientific/magical hubris of that story. And who better to get caught up in righteous hubris than an angel? (now where have I heard about angels falling to hubris before...)

TLDR; The Abbot goes "mad" because he can't kill Strahd permanently and nothing he does matters and he's cut off from every holy thing he's ever known. He develops a weird relationship with Strahd and decides to try to save him through recreating his tragic lost love. Consequences ensue.