Euclid Lucifuge

Euclid Lucifuge is the younger brother of Grayfia Lucifuge and a member of Khaos Brigade's Qlippoth. He was considered as Rizevim Livan Lucifer's right arm.

Appearance
A young looking man with silver hair that is tied in a braided hairstyle and wears a silver robe with detailed accessories.

Personality
Euclid is a calm and collective individual with a ruthless and manipulative side to him as well. A fanatic Lucifer loyalist, he also follows the law of the Lucifuge clan to obey the Lucifer's lineage as he's loyal to Rizevim Livan Lucifer. Euclid was so dedicated to the Lucifuge law of obedience to Lucifer that he held great disdain towards his own sister simply for not supporting Lucifer. Euclid also shares Rizevim's ideals of what a "Devil" should be, believing that it is their job to be evil, manipulative, brutal and ruthless.

Euclid is shown to be completely obsessed with his sister Grayfia, going as far as to create a Replica of a Boosted Gear which is "Red", similar to Sirzechs who is also "Red". His obsession with Grayfia is so extreme to the extent that he wanted to make Rossweisse his "sister" due to their similarities. This obsession, however, combined with his fanatic loyalty to Satan Lucifer also created tremendous disdain towards Grayfia for abandoning her role as Lucifuge, even going as far as to say that she "went so low as to become a servant of the Gremory". Referring to Grayfia's position as the Queen of Sirzechs who came from the Gremory clan.

In Volume 17, it was revealed that for countless years Euclid was emotionally torn between his love towards his sister as well as his dedication towards his duties as a Lucifuge, due to Grayfia defecting from the Old Satan Faction, betraying Lucifer which Euclid consider to be atrocious as a member of the Lucifuge Clan, Euclid became immensely nihilistic, no longer take interest and value in anything only desiring to create and experience chaos. To this end Euclid willingly followed and supported Rizevim in committing many atrocities, such as becoming terrorist causing tremendous damage and chaos to the Vampires' homeland as well as launching an assault on Auros Academy endangering the lives of innocent people and destroying parts of Auros Academy simply to spite Rias and Issei showing utterly no remorse for his actions.

History
Like his sister, Euclid was part of the Old Satan Faction but went missing after the Old Satan Faction lost to the Anti-Satan Faction and was presumed dead. At some point in time, he told Rizevim about Ophis' stolen power, the Holy Grail, the proof about the other world, and 666 (Trihexa).

The Legend of Oppai Dragon and his Lively Companions
Euclid appears in Volume 14, where he helped the "Nilrem" and "Hexennacht" Magicians sneak in Issei's town. After Issei and the others successfully repel the Magicians from both groups, he teleports Issei and his friends to a factory which they built through magic in the Dimensional Gap, where he summoned Grendel to battle Issei. After Issei and Grendel fought for some time, Euclid ordered Grendel to stop, claiming that the experiment was a success and that they needed to head to Vali's place to assist them as they were having some trouble. Before leaving with Grendel, Euclid reveals his identity as Grayfia's brother to Issei and his friends, much to their surprise.

In Volume 16, Euclid was mentioned by Vali as one of those that block him on his way to the basement of the Tepes Castle. He later appears in front of Issei while Issei was exterminating the mass-produced Evil Dragons. Much to Issei's surprise, Euclid reveals a Boosted Gear Replica that he made after copying the Boosted Gear using the remains of Issei's previous body and the souls of famous Dragons. Euclid was initially able to overwhelm Issei easily, revealing that his strength is close to that of his sister. Issei, however, was able to counter back using his newly found power. Euclid then retreats with Rizevim and Lilith after Rizevim orders it.

In Volume 17, Euclid appeared in Tokyo during Issei and Rossweisse's date much to their surprise. He later appeared in Auros, kidnapped Rossweisse, and was pursued by Issei and Rias. Euclid then revealed his goals before killing the magicians who were allied with them, effectively destroying part of the Auros Academy. Euclid and Issei then had a rematch among themselves, which ended in Euclid's defeat and his replica was destroyed. He was then taken captive by the Devils.

Power and Abilities
Immense Demonic Power: Euclid has yet to demonstrate his full powers, but Azazel mentions that he was powerful enough to lead the Khaos Brigade himself. His aura is said to be similar enough to his sister Grayfia's that he was able to get past the barriers protecting Kuoh Academy and let Stray Magicians in without detection. In fact, during his short battle against Issei, Euclid reveals that his strength is equal to that of his sister, Grayfia Lucifuge, who is said to have Satan-class powers.
 * Teleportation: He can use transportation magic, demonstrated when he summoned Grendel and sent him to Vali far away.
 * Dragon Shot : Issei's signature move that was copied by Euclid, along with the Replica Boosted Gear. Euclid fires a beam of energy by concentrated energy from his hand that's been enhanced by his Boosted Gear, unlike Issei's Dragon Shot, Euclid's version is a mixture of red and silver. Euclid may no longer be capable of this ability after losing his Boosted Gear Replica.

Master Inventor: Through his own methods, Euclid was able to create a replica of a Longinus, something that not even Azazel, the leading expert in Sacred Gear research, could achieve as stated by Ddraig.

Equipment
Boosted Gear Replica: Euclid was able to create a replica of Boosted Gear by collecting information of the Red Dragon Emperor's soul and the Sacred Gear from Issei's original body left in the Dimensional Gap by using the Holy Grail. Unlike the original Boosted Gear, Euclid's Boosted Gear appears on the right hand with silver lining. While its potential is weaker than the original, Euclid demonstrate exceptional mastery of it to the point, he surpasses Issei who uses the original Boosted Gear. Even Ddraig admitted Euclid can bring out the Red Dragon Emperor's power to the maximum. The Sacred Gear has a program that destroys itself if Euclid should ever be defeated, which did so after his battle with Issei in Volume 17.
 * Boosted Gear Scale Mail: Euclid is able to use the Balance-Breaker of the Boosted Gear by sacrificing the souls of several famous Dragons, since they are unable to make a copy of Ddraig's soul. The armor looks like Issei's Scale Mail, albeit with slight variations. Like the Balance Breaker of the original Boosted Gear, Euclid can multiply his power any time he wishes but at the cost of a large amount of his stamina and demonic powers. During his short fight in Volume 16 with Issei Hyoudou, Euclid was able to overwhelm Issei with minimal efforts in this form (despite the fact that Issei used his Cardinal Crimson Promotion).

Trivia

 * While Euclid held hatred towards Sirzechs for his existence as a Super Devil, as well as having Grayfia's love and affection. Ironically just like Sirzechs, Euclid has an immense sister complex.