Also called "The Snake" and often "The Society" in short, Ouroboros searches for the Sept-Terrion, ancient artifacts bestowed by the Goddess Aidios, in order to realize their master plan, the "Orpheus Final Plan". Of the artifacts discovered, the Aureole was eventually recovered by Campanella after the battle against Weissman, and given to the Grandmaster. Campanella took the wand held by the Third Anguis and in Zero and Ao no Kiseki, Mariabell attempted to create the Zero Treasure in replacement to the original Mirage Treasure who died.
Nothing is known about the Ouroboros Grandmaster except that they possess a weapon made from The Outside Reason, the same obtainable source which the master used to give Leonhardt his Kernviter, and The Wand to Weissmann. It is revealed in the Sora no Kiseki Drama CD -The Ouroboros Report- that the leader is a female. The leader is speculated to be Aidios, but nothing has been confirmed yet as of Trails of Cold Steel II.
Ouroboros is led by a shadowy figure known only as The Grandmaster. Underneath the Grandmaster are various positions or ranks, such as the Anguis and the Enforcers.
Ouroboros' military is mainly composed of soldiers and machines, but Ouroboros only rarely intervenes "openly" in matters; most of their work is done through subterfuge and deceit.
The First Anguis: Speaks during a conversation in Trails in the Sky The 3rd, otherwise anonymous. Known to be a man
The Second Anguis: Vita Clotilde (The Azure Abyss)
The Third Anguis: George Weissmann (The Faceless)
Also known by his alias Professor Alba, he was the main antagonist during the Sky series, manipulating most of the events happening during and before it in order to obtain the Aureole, the sept-therion of space. He is responsible of brainwashing Josua. He is eventually turned into salt by father Kevin Graham at the end of Second Chapter.
The Fourth Anguis: Speaks during a conversation in Trails in the Sky TC, otherwise anonymous.
The Fifth Anguis: Speaks during a conversation in Trails in the Sky TC, otherwise anonymous, but known to be an elderly man. Is rumored to be either the Eight-leaves-one-blade swordmaster Yun Ka-fai, or Blackhorn, the 8th dominion of the Grailsritter.
F. Novartis (The Professor) Head scientist of the Thirteen Workshops, which manufacture Ouroboros' robots. One of his creations was Renne's Patel-Matel. A typical mad scientist figure, he only cares about his experimentations and little else. In Ao no Kiseki he created the Aions, three Goldias-class robots like Pater-Mater, one of which is defeated by Kevin and Ries. Patel-Matel sacrifices himself to destroy the second protecting Renne one last time. Finally Lloyd and the party defeat the last with Dieter inside of it, but at the last moment Doctor Novartis appears and warps away with his creation.
Arianrhod (The Steel Maiden )
A stern looking young woman dressed in full medieval knight armor who wields a gigantic lance. She has mastered every school of martial arts, possesses a strict moral code, and shows no mercy to her enemies. She held a high expectation for Leonhardt and expected him to someday surpass her. She claims to be the legendary "Valkyrie" of the Erebonian Empire, who lead the Empire's elite cavalry forces into battle 200 years before. She is one of the most powerful figure in the Ao installment. Arianrhod also commands a special and powerful team of Valkyries who are confronted by the heroes several times. After her defeat, she teleports herself and later leaves Crossbell City with the other Ouroboros' members. Also appears in Trails of Cold Steel briefly and helps Class VII.
The Enforcers can be considered to be the "officers" of Ouroboros. They are lesser in influence, but their physical capabilities can rival those of the Anguis
Campanella (The Fool) A young man with a tattoo under his right eye. Although he looks like a normal young man, according to Joshua, even after his days as a Legion Candidate (about 7 years ago) Campanella hasn't appeared to change at all, raising debate whether he is a human or not. He serves as the watcher for Weissmann's plan and ultimately retrieves Weissmann's wand and gives it back to The Leader. Campanella has appeared in both Sora No Kiseki and Ao no Kiseki.
No. I: McBurn (The Almighty Conflagration) Despite his lazy attitude, even amongst the Legion, McBurn's strength is top class. Wielding flames as his weapon, it is said that McBurn's strength is able to match even that of Arianrhod. In order to further the goal of Ouroboros, McBurn has appeared in the Erebonian Empire. It appears that McBurn knows something about the "Power" which sleeps within Rean's true form.
No. II: Leonhardt (The Bladelord)
No. III: Nothing is currently known about this character.
No. IV: Nothing is currently known about this character.
No. V:: Nothing is currently known about this character.
No. VI: Lucciola (The Bewitching Bell) A woman who uses fans as her weapons, she excels in using a combination of fire and wind Arts, bolstered by her power to summon mythical creatures. Her most dangerous ability, and that which makes her such a formidable enemy, is her skill to create illusions with her bells. She was originally from the Harvey travelling circus like Scherazard. She is also respected as a sister by Scherazard but she mysteriously disappeared after the circus is disbanded. It is revealed towards the end of Sora No Kiseki that Luciola held feelings towards the ringmaster of the Harvey travelling circus, but sadly that love was one-sided. After she realized that the circus was going to be disbanded and that she will never see the man she loves again, she decides to kill the ringmaster under a belief that he would remain hers alone. After she lost against Estelle and the others, she fell from the Liberl Ark and it is currently unknown whether she survived or not. Although in Ao no Kiseki, there is a fortuneteller who told the party a story that sounds suspiciously similar to the one told by Luciola.
No. VII: Nothing about this character is currently known.
No. VIII: Walter (The Direwolf) A former martial artist of the Calvard Republic's renowned Taito style, just like Zane Vathek, with whom he shares a history. Walter has tremendous power, as he is capable of destroying large castle gates with one blow.
No. IX: Sharon Kreuger (The Severing Chains) Sharon is revealed to be a member of Ouroboros during Trails of Cold Steel, declaring herself as a "Legion in hiatus". She has also served as the Reinford family's maid for approximately seven years.Bleublanc (The Phantom Thief) A masked man with a white cape, often seen with a rose. He was a famous thief from Erebonia under the alias "Phantom Thief B". He is obsessed with beauty and saw Kloe as a charming woman, Estelle calls him "The Masked Pervert". He cooperated with Weissmann's plan to steal "Hope", because he thinks that the faces of those that resist and cling on to hope are beautiful. He goes to Crossbell in Zero no Kiseki and is part of one subquest where he steals a statue and hides it in the mayor's bedroom. He also talks to Mariabell via a mobile phone in Ao no Kiseki. He also appears in Sen no Kiseki testing Rean and keeps a close eye on Class VII.
No. XI: Nothing about this character is currently known.No. XII: Nothing about this character is currently known.
No. XIII: Joshua Astray (The Black Fang):
No. XIV: Nothing about this character is currently known.Renne Hayworth (The Angel of Slaughter):
Ouroboros has a number of associates operating under their purview.
- Shirley Orlando: Randy Orlando's cousin and ace jaeger of the Red Constellation, nicknamed the "Bloody Shirley".
- Jorg Rosenberg: The elder and head of the Rosenberg Studio, one of the Thirteen Workshops residing in Crossbell State.
- Altina Orion: A young girl from the Black Factory who commands a semi-sentient archaism named "Claimh=Solais", later revealed to be an undercover agent of the Ironbloods, codenamed "Black Rabbit".
- Gilbert Stein: A Jenis Alumni and former secretary of Ruan's former mayor, Maurice Dalmore. He entered the organization for even higher ranking.
- Jester Corps: The Jaeger Corps responsible for the Imperial BG Branches Attack Spree incident under Campanella's order. After the Corps' destruction thanks to Cassius's leaderhip, the remnants went underground whilst unknown they were just a decoy to lead Cassius away for completing the Gospel Plan.
- Duvalie: Head knight of the Stahlritter, a battalion of knights subjected under Arianrhod's loyalty.
- The organization name literally means: "self-eating/self-receiving/endless serpent"
- By the symbol's own definition, the snake eating its own tail represents the cycle of life, death and rebirth.
- It is speculated by fans that the primary members of Ouroboros, the Anguis and Enforcers, have traits that correspond with the Major Arcana of Tarot. This speculation likely stems from members whose number is similar (22, or 23 if Campanella is considered) to the number of arcana (22).
- By a similar vein, 23 is the minimum number of bells in a carillon (a musical instrument generally housed in bell towers), and bells play a prominent role in the Trails storyline; in the name of places such as Crossbell, and in overall presence in many locations, like Rolent and at Thors Military Academy.
- For mysterious reasons, Ouroboros never attempted to retrieve Leonhardt's sword Kernviter after his death, as it was forged by the Grandmster's power.
- Some also claim that the secret society is involved with the Arca of Recluse incident during Trails in the Sky the 3rd, because the password "ORPHEUS", which was already present in SC onboard the Glorious, is also a password for a group of thieves aboard their airship.