I'm not entirely sure, but I assume Vanitas is one of the main characters. There might be other characters that play important roles in the story as well, but without more information, it's difficult to name them.
One main theme could be the struggle between light and dark, as Vanitas is a character associated with the dark side. Another might be identity, since he has a complex origin.
The main themes include identity. Vanitas is trying to figure out his place in the world, and Noé is also on a journey of self - discovery. Additionally, there's the theme of good vs. evil, as they deal with the darker aspects of the vampire society and the possible misuse of the power of Vanitas. And the theme of friendship, as they rely on each other in their adventures.
One of the main themes is the exploration of identity. The characters in the 'Vanitas' light novel often struggle with who they are and what their purpose is. Another theme is the relationship between light and darkness, both literally in the context of the story's magic system and metaphorically in the characters' moral compasses.
The Vanitas no Carte manga has come to an end. The creators completed the story and provided closure for the fans. It was a memorable journey throughout.