Siegfried was a member of the Hero Faction. He was one of the top two swordsmen of the Khaos Brigade alongside Arthur Pendragon of the Vali Team and was known as The Demonic Sword User and "Chaos Edge" Sieg.
Siegfried was a handsome young man with silver-white hair and red eyes. Issei even compared him to Yuuto saying he looks like a "white Kiba". He, just like other members of the Hero Faction, wore a gakuren, and on top of it, a priest's coat, similar to Freed Sellzen. He also wore a belt that held his five Demon Swords and a Light Sword, which were around his waist and legs, forming a sword skirt.
Little has been mentioned of Siegfried's personality besides the fact that he was a dedicated and analytic swordsman and the rival of Arthur Pendragon. He has also shown to have a little regard for his own life using five Demon Swords that cut down his lifespan with no regard when overused and enjoyed fighting against strong fellow swordsmen.
He can also be quite arrogant and cold, mocking the Gremory group for their weak attacks and fighting spirit in the wake of Issei's death (at the time). This would be his downfall in the end.
Siegfried was created as a test-tube baby from multiple genetic patterns at the Sigurd Institution, who were trying to create the "True Descendant of Sigurd" who can use Gram by gathering those who carry his blood. The children of the institute are made from different patterns of genetics. The institute tried to make Sigurd's descendant artificially, to which Siegfried himself was artificially created. He was the only one to be able to handle Gram and was Lint Sellzen's teacher at some point.
In the past, Siegfried worked for the Orthodox Church and was trained in the same institution that trained Freed Sellzen where he gained his white hair due to several experiments. He was a top warrior in the Catholic, Protestant and Orthodox Churches, bearing the nickname "Chaos Edge" Sieg (魔剣ジーク, Kaosu Ejji Jīku), but eventually left the Church and joined the Hero Faction, where he had started a rivalry against Arthur Pendragon and was very upset when Arthur joined the Vali Team.
In Volume 7, he is seen discussing with Cao Cao on their next course of action.
He made his first official appearance in Volume 9, while he and the rest of the Hero Faction are at Kyoto, kidnapping the leader of the Youkai with the intention of using her as a substitute to open the Dragon Gate and summon Great Red. He later fought Kiba and Xenovia by himself and defeated them with ease after revealing his Balance Breaker. When Sun Wukong came, he attempted to fight the monkey but was defeated in one attack. He and the other members of the Hero Faction were then forced to retreat.
In Volume 11, he came to the dimension created by Georg using Dimension Lost and had a rematch with Kiba, resulting with the latter cutting off one of his Dragon arms. After the sudden appearance of Shalba Beelzebub who appeared with a kidnapped Leonardo who forcefully activated Leonardo's Balance Breaker, Siegfried and Georg take Leonardo and retreat.
In Volume 12, he and the members of the Old Satan Faction went to Ajuka Beelzebub's hideout in the human world intending to form an alliance with Ajuka but were rejected, He then fought against Yuuto for the third and final time. During the fight, Siegfried injected the blood of the original Satan into himself which he called Chaos Break. This made his body undergo a demonification process where he transformed into a monstrous spider and fused with his Demon Swords and Sacred Gear. With this new form, Siegfried easily overwhelmed all the members of the Gremory group, who still hadn't recovered from Issei's 'death', cutting off Yuuto's left arm and injuring both of his legs. The battle was overturned when one of Issei's Evil Pieces transformed into the Ascalon, giving Yuuto renewed strength and allowing him to injure Siegfried. Siegfried finally lost to Yuuto after his strongest Demon Sword, Gram, abandoned him and chose Yuuto as its new wielder. As he received attacks from the Gremory group, with Yuuto dealing the final blow by stabbing him with both Gram and Ascalon, his body starts to crumble. After that, when asked by Yuuto on why didn't he use the Phoenix Tears, Siegfried responds by saying that when using the doping of the Satans' blood, they can't heal by using Phoenix Tears as his body crumbled to his death.
Red Dragon Emperor of the Blazing Truth × White Dragon Emperor of the Morning Star: The True Dragon(s) of the Kuoh Academy
Siegfried was mentioned in Volume DX.4, by Jeanne after the Hero Faction started their conversation at the Vatican and felt better if he was alive. They considered him the coldest among the members in the Hero Faction and the most wicked as well and Cao Cao believed if he was alive they wouldn’t set the Vatican as their meeting place.
Powers & Abilities
Natural-Born Demon Sword Wielder: Due to being created with the genetics of the original Siegfried, Siegfried is a capable of wielding Demon Swords, especially the Demonic Sword Emperor Gram without suffering the immediate effects of using it. Yuuto Kiba noted that the only reason that Siegfried couldn't use Gram to its fullest potential was due to the fact that his Twice Critical (a Dragon-type Sacred Gear) clashing with Gram's Dragon-Slayer attribute.
Master Swordsman: As a former top warrior from the Orthodox Church, Siegfried was a master swordsman said to be just as renown as Arthur in the Khaos Brigade. He could handle fighting fellow swordmasters such as Kiba, Xenovia, and Irina at the same time without getting serious; his sword skills are further supplemented thorough the use of his Sacred Gear; allowing Siegfried wield three swords at once. By using his Balance Breaker, he can wield all five demonic swords and light sword at the same time, dominating Kiba and Xenovia with superior dexterity in their second fight.
Immense Speed: From his training as an exorcist, Siegfried is extremely fast. He can easily fight both Yuuto and Xenovia at the same time using just a minimal effort.
Twice Critical (龍の手, Tōwaisu Kuritikaru): Siegfried's Sacred Gear is a sub-species, instead of a gauntlet, it creates a silver Dragon Arm on Siegfried's back and doubles his power.
- Chaos Edge Asura Ravage (阿修羅と魔龍の宴, Kaosu Ejji - Asura Revijji): Siegfried's Twice Critical's sub-species Balance Breaker, which allows him to have four Dragon Arms growing out from his back, with his power doubling for each. As a result, Siegfried obtains 4 Dragons arms in addition to his real arms.
- Gram (グラム, Guramu): Also known as the Sword of the Sun, it is the strongest Demon Sword. Known as the Demonic Emperor Sword (魔帝剣 Mateiken), it is a Dragon Slayer sword with the destructive power of the Holy Sword Durandal. Gram was the first out of his Demonic Swords to reject Siegfried and chooses Yuuto as its new wielder.
- Balmung (バルムンク, Barumunku): A Demon Sword from Norse mythology with a drill-like aura. It is capable of creating powerful whirlwinds.
- Nothung (ノートゥング, Nōtungu): A Demon Sword that specializes in sharpness.
- Tyrfing (ディルヴィング, Diruvingu): A Demon Sword that specializes in destruction.
- Dáinsleif (ダインスレイヴ, Dainsureivu): A Demon Sword that creates huge pillars of ice from the ground.
Light Sword: Siegfried wields a Light sword in battle against devils, which completes his six sword style using his Chaos Edge Asura Ravage.
- The Dragon Arm(s) created by Siegfried's Twice Critical were silver in color, the same color as his hair.
- His current hair color was due to the training he received during his time in one of the institutions of the Church.
- So far, Siegfried is the only named Sacred Gear possessor to die in the series overall.
- Siegfried can mean "victory and peace" or "triumph and sanctuary".
- Siegfried is the second Artificial Human to appear in the series, the first being Freed Sellzen, and the third being Lint Sellzen.
- Siegfried is the second character to be killed by Yuuto Kiba, the first is Freed Sellzen. Coincidentally, they're both Artificial Humans created by the Sigurd Institution.