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Aries Taurus Gemini Cancer Leo Virgo Libra Scorpio Sagittarius Capricorn Aquarius Pisces
Saints of Gemini
The sign of Gemini refers to the mythological twins Castor and Pollux, and so the Gemini Saints always come in pairs. Their relationships are fraught with tragic sibling rivalry, although the struggle doesn't end there. They are ultimately their own worst enemy, fighting long, hard battles between opposing sides within themselves. Saga and Kanon are the twins of modern times in the original Saint Seiya, Aspros and Defteros are the twins of the 18th century in Lost Canvas, and Cain and Abel are the twins of the 18th century in Next Dimension.
Gemini Cloth

Gemini Saga
There's no way around it, Saga has a split
personality complex. He also likes to think out loud.
Alone.. In the bathhouse... Naked.... But I digress. It all
  started back when Kanon planted the idea to assassinate
  Athena and the Pope into Saga's head. Honorable and
  loyal Saint that he was, Saga was shocked by this
  suggestion and promptly dragged his twin brother
off to prison. Still, he was haunted by Kanon's last
  words: that they shared the same blood, so the same
  evil dwelled in Saga's heart. Finally, when the Pope named
  Sagittarius Aiolos as his successor, Saga snapped.
He assassinated the Pope, tried to murder Athena,
  and sent Capricorn Shura to eliminate Aiolos when
  he interfered. This let Saga go about masquerading
  as the Pope without anyone questioning his position.
But his inner struggle raged on, and when at last
the real Athena confronted him, his devotion to
her overcame his madness, and he chose to
commit suicide rather than raising a hand
against his beloved goddess.

Gemini Kanon
Kanon had always been very ambitious, and
saw nothing wrong with using his god-given powers
to take what he wanted from life. But when he proposed
killing the newborn Athena and taking over Sanctuary, his
twin brother Saga had heard enough. He easily overpowered
Kanon and put him into Cape Sounion prison, leaving him to  
 drown by the relentless waves of incoming tide. Luckily,
Kanon found Poseidon's Trident behind a wall and was  
transported to the underwater city of Atlantis. There  
he met with the god Poseidon, who instructed Kanon  
how to revive him back into the world. Kanon had
no intention of doing that. Going by the name Sea
Dragon, he decided to rule in Poseidon's stead.
That plan didn't work out either, and as he saw
Atlantis get swallowed by the sea, he recalled
the warm love of Athena that kept the waves
at bay in Cape Sounion prison, and at last
resolved to embark on the long road to
redemption by taking his brother's
place as the Saint of Gemini.  


Gemini Aspros
Aspros loved his twin brother dearly, and
and hated the many abuses Defteros suffered at
the hands of his peers for being born under the wrong
star. He promised that one day he would become so strong
that Defteros wouldn't have to live in the shadows. Aspros
did indeed rise quickly through Sanctuary's ranks, but the more
he watched Defteros train, the more doubts festered in his heart.
Did his brother truly want to stand beside him or to take his place?
The breaking point came when the Pope named his successor to be
Sagittarius Sisyphus. This was a heavy blow to Aspros' ambitions,
so he decided that he would take the holy seat by force. He made
Defteros his puppet using Genrou Mao Ken and sent him to murder
the Pope. The Pope saw right through this plan, however. He
informed Aspros that Sisyphus had already declined the
Papal position, and Aspros was next in line. The only
thing left was to test Aspros' heart. The same test
he had just spectacularly failed. Hearing this
Aspros killed himself, but not before
vowing revenge from the grave.

Gemini Defteros
While his twin Aspros was coddled and
praised, Defteros was reviled as the evil brother
born under a star of chaos. He was obligated to wear a
mask and forbidden to watch the training of a Saint. Still,
Defteros looked up to Aspros, and hoped that by accepting
his role as his brother's shadow he could make him shine all the
brighter. But after Aspros made him his puppet and sent him to
murder the Pope, Defteros was forced to destroy him to protect
Sanctuary. Tragic as this was, it also freed Defteros to pursue
his own destiny. He left to train in the volcanoes of Kanon Island to
cast aside all weaknesses, embrace  
the power of his chaos star, and
become a demon. In this way he
prepared for the coming Holy
War, and when he met his dead  
brother again as a Gemini Saint,  
 he was able to surpass him and  
cleanse his heart of  
the evil it bore.  
Gemini Cain & Abel
Cain is a paragon of kindness and justice. Abel embodies ambition and greed. Each calls the other brother his shadow, but whether they are two people or the split personality of one is still unclear. While they seem to have separate bodies, but when one brother appears the other gets a headache and disappears. What is clear, however, is that Abel is a traitor to Athena and is interested in working for Hades.
Gemini Techniques
Illusion Gemini Labyrinth*
Gemini is able to create illusions for his enemies, most notably the illusion of an endless corridor where they could run for hours without moving an inch.
Astral Projection Astral Projection*
Gemini is able to remotely project his consciousness elsewhere, even to multiple locations simultaneously, and appear in full armor to face an opponent. When projected in this way, he has access to most if not all of his abilities.
Genrou Mao Ken Genrou Mao Ken
(Demon Emperor's Delusional Fist)

Gemini punches towards his target and releases a beam of energy through his fist and into their forehead. This beam penetrates straight to the brain and puts the target under Gemini's control. The brainwashing effect wears off after the victim completes whatever mission Gemini gave them or, as in the case of Leo Aiolia, upon seeing somebody die in front of them.

Episode G
says that this attack is exclusive to the Pope, so it is unclear whether it is normally part of the Gemini arsenal. When acting as Pope, Saga used it on both Capricorn and Leo, but Aspros used it on Defteros when he was just a Gold Saint. However, given the questionable standing of Lost Canvas as canon, it may not be a valid counter-example. It still is relevant to point out that the Bronze Saint Phoenix Ikki has a lesser version of this attack, so it would make sense for a Gold Saint wielding it as well. Especially Gemini, who already has mental powers in his arsenal.
Short Range Blast Short Range Blast*
Gemini can shoot a quick energy ball or a barrage of lasers at his opponent.
Long Range Blast Long Range Blast*
Given a bit of preparation time, Gemini can trace the Cosmo of his intended target and launch a powerful beam of energy at their remote location.
Another Dimension Another Dimension
Gemini can open a rift in spacetime and send his target(s) to another dimension or, to be more specific, a kind of inter-dimensional passageway that's outside of any solid realities as we know them. He can then close off the space and trap those who were sucked into it in limbo to wander eternally between dimensions. A scary attack, to be sure, but victims have been known to escape its grasp. Cygnus Hyoga, for example, got dumped in the middle of the Libra temple despite being hit with the full force of Saga's Another Dimension.
Golden Triangle Golden Triangle
This is technically not a Gemini attack, but Kanon uses it when he's still a Marina of Poseidon. It is a reference to the Bermuda Triangle's purported ability to warp reality and make objects vanish from this world. Its effect is identical to Another Dimension, although Ikki comments that Kanon's attack is weaker than Saga's.
Black Eruption Black Eruption
This attack is unique to Defteros. It is the personification of his power as one born under a chaotic star, honed by his rigorous training on the volcanic Kanon Island. Lava to floods in and erupts from the ground all around Defteros, incinerating his enemies.
Galaxian Explosion Galaxian Explosion
This ultimate attack of the Gemini Saints has the power to rip apart whole galaxies! Indeed, that is exactly what happens. Gemini creates a galaxy using his Cosmo, enveloping his victim in a spacefield of stars and planets, and then triggers the celestial bodies to burn up and explode in a blaze of cosmic proportions. Few can survive this awesome display of raw power.
Group Techniques
Athena Exclamation (Light) Athena Exclamation
The honor code of the Saints dictates that all battles must be one on one, but Athena Exclamation can only be performed by three Saints. It has the force of the Big Bang, and is so overpowered that Athena herself had it banned. However, Saints have been known to use it under extreme circumstances.
Athena Exclamation (Dark)
Supernova Sunlight*
The Zodiac constellations have long bathed in the light of the Sun, and the Gold armors that represent them have absorbed an infinite amount of sunlight. To perform this incredible blast of energy, all the Gold Saints focus their Cosmo into the tip of Sagittarius' arrow, thereby fusing their powers as one.
This attack was used to break through the Wailing Wall by bringing the full intensity of a star into the darkest depths of Hell. Although it is said that Athena Exclamation has the force of the Big Bang, Supernova is undoubtedly more powerful, since it utilizes the combined strength of twelve Gold Saints instead of three. It instantly disintegrates everything in its vicinity, including those who cast it, and sends waves of devastation rippling outwards. 
Aries Taurus Gemini Cancer Leo Virgo Libra Scorpio Sagittarius Capricorn Aquarius Pisces

Knights of the Zodiac

*This technique does not, as far as I know, have an official name. I just gave it a descriptive name.

Saint Seiya (also known as Knights of the Zodiac), all of its spinoffs (Lost Canvas, Episode G, Next Dimension, etc), all characters, art, and story is copyright Masami Kuramada. No copyright infringement is intended.
Credit for Genrou Mao Ken picture to SaintSeiyaPedia, and for the Saint Cloth picture to Pharaon Website.