Lily Potter's mother was a Belmont by birth and was the one who gave her life for her grandsons that Halloween. Lily refuses to abandon an apparently squibbed Harry and instead leaves James to return to her mother's family.

A Wrong-Who-Lived crossover with castlevania where Lily's mother, and by extension Lily and Harry, are Belmonts by birth. Something she only shared with her daughter during the war.

Refusing to leave Harry, Lily leaves James and seeks out the remnants of the Belmonts using a Grimoire her mother left her. The Belmonts take them in and, thanks to the extensive knowledge of blood magic and various forms of black magic, they are able to treat Harry's condition and heal him. Using a form of blood magic developed long ago by Alucard and Sypha Belnades, Harry has his paternal heritage overwritten using the stasised blood of one the many various past Belmonts of renown. Harry Potter ceases to be in his place stands Heinrich Johhanes Belmont.

Raised in the Belmont Hold in Wallachia alongside his cousin Julius, Heinrich is forced to return to the land of his birth to attend Hogwarts due to his name still being on their rolls due to still being born there; an unfortunate consequences of ICW law banning homeschooling in the aftermath of WW2. His arrival signaling to Magical Britain that something is afoot. After all, the Belmonts were notoriously secretive and only seen in times of great turmoil.

Dumbledore, unaware of Lily's heritage, is rather unnerved that a Belmont has come to Hogwarts; even as a student and child. Completely ignorant that Heinrich is the boy he once erroneously declared a squib. He can only hope the boy chooses to become an ally when he comes of age.