Defteros of Gemini

Deuteros physically resembles the brothers Saga and Kanon. Deuteros has an athletic physique; as can be seen, he is tall and has blue hair. His most striking feature is his dark skin.

Despite Deuteros's exacerbated attitude, it can be inferred that his personality was previously rather timid, and that he has always shown great integrity. In fact, he has always been very respectful of the Sanctuary, even though it has shown great injustice towards him. Deuteros is encouraged to go to Star Hill, but he was very upset when he saw his brother violating the rules of use of that space. Deuteros also holds great respect for Sage and Asmita. Similarly, Deuteros eventually erased Dohko's memories about the blood and the Cloth of the goddess Athena, maintaining that it must remain a secret known only to the Pope. He never managed to become the ruthless demon he wanted to be, although this simple facade undoubtedly helped him resist the Imperial Satan, but Deuteros couldn't bring himself to kill his brother, preferring to die in order to allow Aspros to recover as a Saint.

Deuteros is Aspros' twin brother, however, the two are treated differently. Within the Sanctuary, it is said that Aspros was born under the brightest constellation, destined to become the strongest Saint, while Deuteros was treated as a spare, a second choice, who had to wear a leather mask and never appear in public. He couldn't watch the other Saints train, much less train on his own. One day, while Deuteros was being punished for appearing in public, Aspros appeared and saved him from punishment, assuring him that he would become strong so that both he and his brother would be accepted as the strongest Saints. However, misfortune arrived at the hands of Yōma of Mephistopheles, who, with his power, influenced Aspros' soul and mind to believe that Deuteros was training and would soon take his place, that Deuteros would become the Gemini Saint. To convince him, Yōma takes Aspros to where Deuteros secretly trains and realizes that his power has grown considerably. Yōma adds a drop of malice to Aspros' mind, and from then on, Aspros begins to despise Deuteros, even constantly humiliating him. When Kokalo is reborn thanks to Aspros removing the seal that held the Berserkers to the Arena of Spirits, Aspros cuts his younger brother's back, telling him it's a disgrace that he couldn't defeat an unprotected opponent. Then he begins to beat all the Berserkers and increase the temperature in the arena. Deuteros confronts Kokalo, who finds it admirable that he faces him despite not being a Saint or wearing a Cloth.

Two years before the height of the Holy War, the Golden Saint Aspros of Gemini betrays the Sanctuary and plots the assassination of Pope Sage of Cancer, driven by jealousy at learning that the Pope had designated Sisyphus of Sagittarius as his successor, not himself. To minimize suspicion, Aspros uses his mind control technique, the Imperial Satan, on his twin brother, Defteros of Gemini, and sends him to Sage. The Patriarch is already prepared and calmly stops Defteros's fist. This causes Aspros to reveal himself and offer to kill his twin brother, begging the Patriarch to turn his back so he won't witness the fratricide. Sage agrees, an opportunity Aspros tries to take advantage of to strike him. It is at that precise moment that Asmita of Virgo, whom Sage had summoned suspecting the Gemini Saint's intentions, is forced to intervene. With a protective barrier, Asmita protects Sage and, lamenting that someone like Aspros has fallen so low, prepares to begin a Thousand Days Battle against him. Aspros repels Asmita's attack by placing Defteros between them and telling him that he will not be his rival, but his twin brother will. Sage asks Virgo to take care of Defteros while he contains Aspros, and it is then that Asmita understands why she has been assigned this task. Through her Tenpō Rin In technique, Asmita enters Defteros's tormented mind, sees his true personality, and dispels all her doubts.

Asmita, by making Deuteros understand that he is, in a way, also responsible for his brother's betrayal and that only he can make the differences between them cease to exist, causes Deuteros to attack Aspros, piercing his chest with his own hands and thus freeing himself from the Genrōmaōken. Before dying, Aspros understands why Asmita's presence was so necessary, as he was the only one capable of bringing his twin to reason, and shortly after performing the Genrōmaōken on himself, he swears to those present that he will return and accede to the Patriarch's throne that had been denied him. Deuteros, who finds himself before his brother's tomb, realizes the presence of someone else in that place, so he quickly attacks them, but is stopped; to his surprise, that other person was Sisyphus, who is surprised that Deuteros and Aspros are like two drops of water. After this, Deuteros tells him that he has heard that the Saint of Sagittarius has declined as a candidate for Pope and then asks him why he made that decision, to which Sisyphus replies that he cannot become the Pope because he will soon be devoured by darkness and that there is no way to avoid it. The Saint of Sagittarius also tells him that there is a certain talent that is beginning to flourish. Hearing this, Deuteros tells him that even after the death of his brother, Sisyphus continues to reject the throne of Pope, and after this, he takes the Gemini Pandora Box and proceeds to leave that place. Some Saints have encountered the Demon of Kanon Island with the purpose of becoming stronger. Two of them escaped after being defeated in seconds. The Saint of Perseus remained against his will, being slammed against the ground by the Demon's foot. The Demon mocks the weakness of the others, which is the reason that increases his fury. Perseus has been totally defeated; the strange being has taken the Medusa Shield between his teeth and broken it with a single bite.

Tenma wants to become stronger, and on the advice of Dégel of Aquarius, he heads to Kanon Island. There, he seeks a "demon" that will make him stronger, but could also kill him. The young Saint encounters a terrified town rife with rumors about the Island Demon, yet they reach a sinister cave filled with bones and blood at the top of the volcano. Bravely, he cries out his desire to be strong, begging to be accepted as a disciple. Deuteros threatens Tenma, who pleads with him. Deuteros tests Tenma's resolve, adding that he will kill him otherwise. Tenma decides to jump and manages to climb the cliff, surprising Deuteros who thought he was dead. Deuteros then confiscates his Cloth. The final test is to stop the imminent volcanic eruption with his Cosmos. Tenma reaches the edge of the crater and successfully uses his Cosmos to influence the volcano, stopping the eruption and saving the island's small town. The young Saint faints, and Deuteros returns. He carries the still unconscious Tenma on his shoulder and places him on the ground with his armor on the ocean's edge. Deuteros is surprised that Tenma succeeded, and also notes that the whole world seems very agitated lately, so he sends this observation to Asmita of Virgo. Asmita explains that while Tenma is indeed dead, he is still trying to master the Eighth Sense, and then they both discuss Tenma's evolution. When Sísifo of Sagittarius, Shion of Aries, and Regulus of Leo execute the Exclamation of Athena, Sísifo dies. Deuteros is then seen on Kanon Island saying that Sísifo was a fool for letting the weak live, but that he died doing what he wanted.

Next, he is seen helping to awaken Dohko of Libra, who was unconscious on Kanon Island, due to the wound inflicted by Hades, the "Soul Wound Flame". Deuteros then soaks his fingers in Athena's blood and pierces Dohko's heart, causing him to awaken. Deuteros informs Dohko that he is on Kanon Island where wounded Saints heal their bodies and that he had been there for a month after being attacked by Hades. Deuteros tells Dohko that Athena's army is heading to the Lost Canvas, to which Dohko decides to go and help, but Deuteros stops him and tells him that if he goes he will not help at all. Deuteros possesses a small vial of Athena's blood, the same from which he took some to awaken Libra. He gives it to Dohko and tells him that he must traverse the 12 temples and offer the blood to the Statue of Athena. Dohko asks him why, if he knew the importance of this secret, he did nothing, and he tells him that he was waiting for the right moment; at that moment the Gemini Cloth appears behind Deuteros and he then wears it. Using the Another Dimension, Deuteros reaches the Temple of Athena, where Dohko and Kagaho were fighting, and takes Dohko and the Athena Cloth, leaving Kagaho the message to inform Hades that Gemini and Libra are going to the Lost Canvas and that he will be defeated at that time. While traveling through the dimension created by Deuteros, they feel an incredible cosmos approaching, so Deuteros partially erases Dohko's memory, making him forget the secret of the Athena Cloth, since only the Patriarch knows of it. He entrusts him with the Athena Cloth and sends him to the Lost Canvas. Immediately, Aspros of Gemini, his older brother, appears, who betrayed Athena and has become a servant of Hades, to search for the Athena Cloth. It is then revealed that Aspros was originally the Saint of Gemini.

In the Temple of Pluto, Alone talks with Pandora, who asks her how she knew about Athena's Cloth. Alone tells her that someone betrayed the Sanctuary, someone who was murdered two years ago for conspiring against the Patriarch, and that this person had approached her to negotiate a new life to avenge himself on the Sanctuary and Athena in exchange for the secret of Athena's Cloth, known only to the Patriarch. Alone mentions that she is already inside one of the evil temples: the Temple of Mars, and it's all because of her ambition to replace the Patriarch. Aspros is in the temple on a throne like the Patriarch's, dressed as such, saying that Athena's Cloth has finally been removed from the Sanctuary. Aspros speaks with a kind of Sage spirit and tells him that he said he would appoint him Patriarch, then makes him disappear and says that he doesn't care if he uses the power of Athena's Cloth to dominate the Sanctuary. Aspros goes in search of Deuteros, entering the Another Dimension that he created. Upon meeting, they exchange blows and words before being transported to the Temple of Mars. Aspros tells Deuteros that he exists thanks to him, as he is his replica. Deuteros notices that the evil temple where they have fallen is similar to that of Gemini and then remembers his childhood, when he and Aspros were young. Aspros bursts in wearing a Gemini Surplice and attacks Deuteros with his Galaxy Explosion, but he doesn't manage to harm Deuteros much, who prepares to attack Aspros, but Aspros uses his Genrōmaōken technique. Once the memories are finished, the brothers stare intently at each other and Aspros tells him that none of that will happen again. He mocks Deuteros, saying that neither the Patriarch nor Virgo are there to help him counteract the power of the Imperial Satan, telling him that his first victim will be Athena. Suddenly, a sea of magma covers the entire temple.

Deuteros tells him that he will never let himself be manipulated again, that that day he vowed to become a demon who would shake everything. He describes how he trained to surpass all limits and show everyone his ego. Deuteros attacks Aspros with a new technique: Mavros Eruption Crust. An incredible technique, but Aspros tells him it's incomplete. The eruption is consumed by the Galaxy Explosion. Aspros reproaches Deuteros for wasting his only chance to defeat him, pointing out that the only technique that can beat him is the Galaxy Explosion. Deuteros is enraged that someone like him uses that power; Aspros tells him that's further proof of his incompleteness, saying that the noble brother he remembers from the past was a lie, that he always manipulated him. Aspros tells him that he is complete, even though he is criticized for supposed wickedness, that his only goal in resurrecting is to use him, kill the Patriarch, the gods, and dominate everything. Deuteros reacts and says that his brother is dead, that he no longer feels anything for him. Both brothers leave the past behind and will be destroyed in the Galaxy Explosion. The clash of both Galaxy Explosions occurs; the battle between light and shadow, good and evil between the two brothers is about to end. As the clash of powers occurs, Aspros stares into his eyes and remembers that since childhood he noticed that look in Deuteros, as if he wanted to copy him, equal him, and remembers how in the past he discovered his brother imitating his techniques in solitude, feeling that look was threatening to him.

Aspros can no longer tolerate that gaze, and one of the two must perish. The entire Temple is destroyed after the deployment of the Gemini technique, and a large hole in the Lost Canvas is caused as a result. Deuteros has lost. Before dying, Deuteros tells him that they will finally be able to see each other as brothers, as in the past; in the end, his technique pierced Aspros's mind. Aspros regains the original color of his hair. Deuteros disappears, leaving only his golden armor in front of his brother.

•Galaxian Explosion: This consists of an explosion of energy spheres that the Gemini Saint releases through his hands. It is said to have the power to destroy stars and even the entire galaxy. Its impact is so devastating that it can completely obliterate them, leaving no trace. •Genrōmaōken: In the form of a punch, a lightning bolt is launched, piercing the opponent and sending a power surge that attacks the opponent's brain, controlling their mind. • Another Dimension: Opens a rift in space to an empty dimension which, with great power, absorbs the opponent. •Arc Geminga: A small magnetic field is created in his right hand, taking the form of a dark sphere that begins to expand until it surpasses the size of Aspros himself. Then, he holds the sphere with both arms raised above his head and, when ready to attack, throws it towards his opponent. Upon reaching its target, the dark sphere envelops the victim, trapping them in its core. From that moment on, the opponent begins to suffer intense pain as their body is slowly crushed and destroyed by the pressure of the magnetic field. •Mavros Eruption Crust: Deuteros summons a mass of explosive lava beneath his opponent, like an erupting volcano. After enveloping the ground in lava, Deuteros places one hand on the ground, supporting the other on the elbow of his outstretched arm, directing an eruption of magma towards the opponent. Deuteros controls lava and summons magma from the depths of the earth to create a volcano-like eruption to incinerate his enemies.