Theories I’d currently buy about The Case Study of Vanitas:
Drinking Vanitas’s blood will do something to Jeanne since he was experimented on and is connected to V!Vanitas.
The Archiviste family is connected to V!Vanitas. V!Vanitas is an Archiviste, and/or the Archiviste family was born under a blue moon...
Thinking about traditional vampire mythology and the way that vampires seem to be “mistakes” in the Formula, vampires may come from dead people in some way, or are “living concepts.”
Vanitas’s earring is from V!Vanitas.
Noe’s teacher is a Juror.
Dominique is connected to Lacie.
Noe’s teacher knows V!Vanitas and possibly Vanitas.
There will be a trick to the narration- Noe’s not actually narrating, he’s an unreliable narrator, or any number of things.