Karl Fei-Ong

Karl Fei-Ong (Carl in the English dub) is the third of Diva's chevaliers and a member of Cinq Flèches. He is voiced by Nozomu Saski in the Japanese dub and by Quinton Flynn in the English dub.

Origins
In 1917, Amshel Goldsmith chooses Karl Fei-Ong to use as a test subject for their new Delta project. He and Solomon Goldsmith introduce Karl to Diva in Germany. When he meets her, he requests that she turn him into a chevalier.

Karl's body is heavily modified by Amshel's experiments, including having the arm Saya destroyed in Vietnam in 1972 replaced with a spiked arm. His traumatic past, Diva's inability to give him the love he sought, and forced conversion seems to have left Karl severely mentally unbalanced. However, Solomon, the only one who could calm Karl's mania, believed Karl's problems stemmed from his being lonely and not seeing that Solomon was always there and watching over him.

Return to Vietnam
He is the chairman of an all-girl's school in his native Vietnam, where he is respected by both teachers and students. The girls themselves do not seem to fear him - they are polite and he is polite in return. Disguised as his alter ego "The Phantom", Karl kidnaps girls that look like Saya in his desire to see her again to finish their fight; before the girls went missing they were all given a blue rose. It's not clear whether he based "The Phantom" on the legend or whether the legend is based on him.

After finding Saya again, Karl becomes completely obsessed with killing her. He considers Saya his hated enemy, his beloved soul mate, and his only reason for living.

During the Red Shield's investigation in the Vietnamese jungle, they discover a secret farming facility owned by Cinq Flèches under the management of both Karl and Solomon. Karl leads an attack on the group, which causes several casualties. Saya later fights Karl, which results in Karl losing his leg in the process and being forced to retreat.

Breaking Shield
Karl finally gets his longed attention from Diva when she requested him to bring her "that boy," Karl (dressed as The Phantom) brings Diva to Red Shield's HQ without Amshel's authorization and begins killing all of the Red Shield's operatives. He encounters Saya, but Hagi distracted him long enough for Saya to escape. Karl escapes the ship along with Diva and manages to wound Joel with his spikes, which would cause him to be permanently crippled.

Death
While in London, he stole the Corpse Corps from Amshel after being outraged when James was given the orders to kill Saya instead of him and went after her while she was at Gray's home. He planned to die together with her by drinking all of her blood. Solomon, who'd come after him at Amshel's request, cuts off Karl's arm freeing Saya's sword arm. Realizing she has too much to live for, Saya stabs him by impaling her own body. With her sword coated in her blood, Karl crystallizes and is destroyed. Solomon mourns his death and tries to explain Karl's actions.

Personality
Although usually calm, Karl can be violent and obsessive, bordering on mental instabilty. His manic behaviour stems from being used as a guinea pig in the Delta Project, repeatedly having his limbs removed and replaced and also being abandoned by Diva and trying to fill the loneliness which is why he turned his attention to Saya.

Relationships with other chevaliers
Karl appears to be the outcast of his group. He frequently works alone, rarely talks to the other chevaliers and is often left out of imporant meetings. The cause of this rejection is hinted at in the anime: like all of her chevaliers Karl loved Diva deeply, however he tried to steal her away and keep her as his own. This undoubtedly was the cause of the rift between him and the other chevaliers, especially Amshel, whom he seems to fear.

Solomon

Solomon is Karl's only friend who displays any sympathy towards him. This sympathy however seems to be the result of Solomon's own guilt - not only was he the one who tricked Karl into becoming a vampire, he also aided in his death. Although Karl is rarely involved with his brother's meetings Solomon phones him to keep him updated. Karl and Solomon are briefly seen "playing" together at the end of episode 29 - Karl pretends to attack his brother with his new arm, but Solomon is much too quick and easily catches him by the wrist.

Amshel

In complete contrast to Solomon, Karl fears Amshel, probably because the organized the many operations performed on him.

Amschel intentionally antagonizes Karl, noticeably by insisting James kill Saya despite the fact Karl volunteered first. Later it is revealed that he does this to deliberately provoke Karl into chasing after her, giving him an excuse to kill him.

James

Like Amshel James appears to have nothing but disdain for Karl, characterizing him as careless or reckless, and seeing his death more as a convenience than a loss to them.

Nathan

Interaction between Nathan and Karl is non-existant.

Powers and abilities
Like all Chiropterans, he is immortal. He has great healing abilities, recovering from stab and gunshot wounds within moments. Stated in the light novel, Chiropterans have the ability to sense other Chiropterans. Karl's ability with this is greater than James Ironside. In his true form, his original power was to make a blade from his hands. After having his right arm replaced by Amshel with a spike arm, he gained the Schiff's ability to crystallize his blood and fire it from his arm. He is also capable of flying as he possesses a pair of wing each located underneath his arms.

His weaknesses, like all chevalier, include Saya's blood and, if Amshel was telling the truth, decapitation and complete incineration of the body. It is unknown whether or not that he, like James, could contract the Thorn.

Manga
In the manga adaption, Karl's appearance and mannerisms are completely changed. He's more childlike and is stated to look several years younger than Riku, who is fourteen. Karl is the only one besides Amshel that Diva cares for. After losing his arm during the fight at Vietnam with Saya, he 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 post-mortem 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. It stays close to Riku and develops a bond with him. At the end of the series, although Charles is dead, his clone lives on with Riku.