Charles

Charles is one of Diva's chevaliers. His apperance is like a twelve-year-old boy. He appears only in the Manga Blood Plus. He is also referred as 'Carl'. Charles has some similarities with the character Karl Fei-Ong of Blood+ anime.

Personality
In some way he feels drawn to the 'berserk Saya'. He also decorated his mansion with blue Roses. Charles cries a lot yet he is very sadistical.

Diva
Karl is the only one besides Amshel that Diva cares for (as shown in manga).

Riku
Charles and Riku have a good relationship. He seems to care about him and trust him. He stays close to Riku and develops a bond with him. Riku even takes a bullet to save him.?

In the Manga
After losing his arm during the fight at Vietnam with Saya, Karl is forbidden from seeing Diva again and loses his status as a chevalier, becoming a living experimental subject for the next generation of chiropterans. He is then renamed Charles by Amshel. Charles (Karl) is still in contact with Amshel and has a sort of friendship with Van Argiano, who is the head of the research team leading the Delta experiments, and Riku.

Saya makes Riku her chevalier because he shields Charles from a bullet. When the group arrives to save Riku, she sees her fallen brother and automatically assumes Charles killed him. Whether he wants to see Saya angry or just to be free of his pain, he doesn't deny it and happily allows Saya to kill him.

Riku isn't told of Charles' death, whose DNA is used postmortem to perfect the Corpse Corps, an army of chiropteran clones with the ability to neutralize the regeneration of other chiropterans. After a failed attempt at a mating experiment between Riku and Diva, Riku leaves with Solomon after Diva throws a tantrum and angered Solomon. He sees one of Charles' clones and believes it to be his friend. Solomon doesn't correct him, instead letting the boy believe it is Charles in the hopes that Riku will lead him to Saya. It is later revealed to Riku by Saya herself that she did kill Charles.

The clone can't speak properly and doesn't have the mannerisms of a human, so it acts like something of a pet. It even has a habit of biting people's arms (like a harmless cat or dog) for blood. At the end of the series, although Charles is dead, his clone lives on with Riku.