Personality
Human
Even as a human child, Ferid has an excellent memory and memorizes things easily, which leads him to becoming bored quickly.
Vampire
I want to see your faces twist in despair
Ferid ruthlessly kills off the Hyakuya orphans in front of Mika and Yū
Ferid is chatty, happy, enthusiastic, playful, and sneaky. He is often described as unpredictable and says things to incite someone's temper but then says he is just kidding. Ferid enjoys irritating Third Progenitor Krul Tepes and Mikaela Hyakuya to a dangerous level, and he has a great deal of fun teasing Mika as well. He is infamous for his eccentric behavior and tends to cause "interesting" things to happen, according to Thirteenth Progenitor Crowley Eusford. He likes to risk having all of his plans ruined just so that he may feel some emotion.
When Crowley suspects a high-ranking noble may be giving information to the humans, Ferid is the first one he suspects. Ferid is self-serving and traitorous to serve his own ends, and he really appears to be assisting the humans somehow. He uses blackmail to stay Krul's hand when she desperately wants to see him dead.
On the outside, Ferid acts kind and polite. However, he keeps many secrets and tells many lies. He is sadistic and enjoys manipulating others in order to torment them. He immensely enjoys crushing the hopes of human children and watching their expressions become filled with despair. He says he wants to hear them scream. He prefers the blood of beautiful boys and girls, and has kept many mansions filled with them over the centuries. Once he loses interest in one to the point of forgetting the child's name, he kills him or her. Regarding age, he claims the 16-year-old Mika is just barely within his preference range. He would like Mika to drink human blood and stop aging as soon as possible, and he frequently brings up the topic when he is alone with him.
Ferid up to no good
Ferid mocks both vampires and humans to his mysterious partner.
Toward his own supporters, Ferid may say carelessly cruel things. His true objective is a mystery, even to his closest followers. He appears to be at work manipulating many things behind the scenes.
He considers the humans to be ugly, insatiable cowards. He also mocks the vampires' boundless arrogance.
History
Ferid carries the Michaela trait and was turned into a vampire by Saito. Since then, he has watched and waited to find other people carrying the Michaela trait and uses the blood of higher-ranking progenitors to turn them into vampires. He uses Second Progenitor Saito's blood to turn Crowley Eusford into a vampire. He manipulates Mika's situation in order to force Third Progenitor Krul Tepes to turn Mika into a vampire as well.