Rewatching Season 3 recently I noticed Count Saint Germain's book. I learned that, like many things in the show, this is a real thing. https://en.wikipedia.org/wiki/The_Triangular_Book_of_St._Germain : r/ castlevania
Castlevania (TV Series 2017–2021) - IMDb
The Original Castlevania Keeps Aging Like Wine | Goomba Stomp