I do not have a theory because there is very little details given, but I am on the verge of connecting the events leading to the story. We just have to wait a few more chapters.
There is this huge connection between Teacher, Vanitas of the Blue Moon, Ruthven, and Naenia. I just know there is and that is what is driving the entire story. Now we know Vanitas knows more than he lets on and only tells Noe what he knows when he has to. He said he had an inkling that Naenia was Queen Faustina. However, despite wanting to stop cursed bearers, he says she is less dangerous as Naenia. Think about if he were to turn her back into a vampire, he would inevitably prevent the making of new curse bearers. What exactly is going on? We know that both the Beastias nor Vanitas want Faustina to come back. Why?
Let’s get on to these connections. So because Noe calls Vanitas of the Blue Moon a woman, I will assume she is one. He is watching the memory, so the voice must belong to a woman. Anyways, Noe points out that Faustina and Votbm look really similar. Even their hair is cut similarly. This leaves a few possibilities. Faustina and Votbm are sisters (some have stated twins but idk how that works out because the story talks about them being born under two colored moons), mother/daughter, of the same clan (I am still thinking they belong to the Archviste clan), or the same person (which I personally do not want).
Now, Teacher has been with Faustina for the longest until Ruthven took over. And we all know both of them do not get along. Does this have to do with Ruthven taking Teacher’s spot? Funny thing is they are both extremely similar. Both of them collect weird treasures as we have seen their office and are known as teachers. Seeing Ruthven’s old personality, you would think they would suit each other (since they exhibited a fun feel to them). How did both their relationships towards Faustina lead her to become Naenia?
I have this little theory that maybe Faustina is Votbm’s kin, so there must be a repercussion that comes along with making one her kin, and so she did not want Vanitas or Misha to go through it. Maybe this could be why the Beastia ganged up on her but we will have to see. I just know that Votbm has previously made someone her kin, and it did not go well.
Moving on, Teacher and Votbm got something going on as well. They are also portrayed very similarly (fun-seeking, educators, curious, powerful, shrouded in mystery). I would say that Noe is much more like Votbm though. I could squeeze in Noe’s connection to Votbm, but I’m not going to simply because that one has like almost no pieces (but I will say that Noe just being found by random old people is hella sketchy). I was thinking that if we combined Noe’s personality and Faustina’s looks, we get Votbm lol. Reversing back, Teacher being fascinated by the Book of Vanitas raises some questions. He was literally studying curse bearers and keeping Louis for that exact reason. Why study curse bearers? Did his research help the Beastias turn Faustina into one? I also find it fascinating that he and Votbm do not have true names. Teacher changes his constantly. I thought it was to avoid becoming a curse bearer but maybe he is just not satisfied with the names he chooses (like Votbm).
I know we have only been given a few pieces of the puzzle, and I was literally trying to connect the dots and hope that maybe someone reading this could figure it out since we got some good theorists out there.