Melchior

Melchior (メルヒオール Meruhiooru) is the son of Sylvester and Florencia and the youngest member of the archduke's family.

Spoiler from Part 4 Volume 8 Despite sharing the haircolour of his father, his facial features and blue eyes make him more reminiscent of his mother.

Like all Archduke Candidates of Ehrenfest, he lives and grows up in a building separate from the main castle to it's north.

Spoiler from Part 4 Volume 8 Since he would never have any opportunity to meet them before being baptized, Melchior was not told about any of his relatives in other duchies, except Constanze and her husband, who had came up in conversations previously.

During their visits to their younger brother both Wilfried and Charlotte have often talked very positively about Rozemyne, but due to not being a blood-related sibling, she was not able to personally visit Melchior

Spoiler from Part 4 Volume 8 He is eager to also join his siblings in performing religious ceremonies and is studying geography very diligently for this purpose. He is also looking forward to borrow the boards from his siblings from which they learned the necessary prayers. His parents have decided that he will only join in the ceremonies the following year, so he can get more used to moving and using his mana. Unlike with Charlotte, who had to stand in for her comatose sister right after her baptism, this year there is no pressing need to push such a difficult and exhausting task onto the boy right now.

In the meeting with his parents right after their return from the Interduchy Tournament Melchior first learned that he had a cousin in Frenbeltag, much to his surprise. His parents explained why they didn't tell him about his relatives from other duchies in the past and said they would soon teach him about them.

Melchior's new room in the nothern part of the Archduke Castle has been prepared while his siblings were at the Royal Academy and Interduchy Tournament. He is very excited to finally meet his adopted sister Rozemyne.

Spoiler from Part 4 Volume 8
 * Zargerecht - Technically Zargerecht is still Florencia's retainer and Melchior's tutor at the moment, but will become Melchior's head attendant upon his baptism.