|“||Power only has meaning if it's put into action... it defines you. Power like that is what rules the world||„|
|~ Seth to Ryu|
Bearing silver skin and an extremely muscular physique, Seth is a synthetic human that lacks clothing or hair; whether he is an android or cyborg is unclear. In his abdomen, enclosed inside a pattern consisting of the Eight Trigrams of Taoist cosmology, is an exposed area, which contains a rotating sphere known as the Tanden Engine, which appears to be the source of his power.
Seth's appearance is rather similar to characters such as Doctor Manhattan (Watchmen), Tyrant T-103 (Resident Evil 2) and Dural (Virtua Fighter). Perhaps coincidentally, he uses both Dural and Tyrants as minions in his appearances in Project X Zone.
Seth is just as intelligent as M. Bison himself, with ruthlessness and evil to match. Unlike M. Bison, Seth is generally very calm and concise, though he displays a fair bit of arrogance, often through his annoying-by-design tendency to laugh and gloat when using his more powerful moves. Seth also demonstrates a deep knowledge of the philosophy of human nature and the pursuits of purpose and self-awareness. This unusual trait, coupled with his endless thirst for power, implies that Seth intends to become his own entity entirely and not be bound to M. Bison as his replacement shell. Notably, while Seth appears to be the only "sentient" enhanced being, his Arcade Mode win quote against another Seth implies that at least one other clone may have developed self-awareness.
However, his desire for power and his philosophical pursuits are a one-sided and neutral affair; he displays very little (if any) morality or respect for life, and values people only for their usefulness to him. Due in part to his ego, Seth will keep his S.I.N. subordinates in the dark in case they plan to betray him - insubordination is something he refuses to tolerate. Seth is of the belief that any power is good power, as indicated during his fight with Ryu in the animated film. In addition, despite his philosophical leanings, Seth displays some form of disbelief in the mystic arts; his Arcade Mode win quote against Dhalsim states that if the latter's techniques were truly mystic, he could not possibly imitate them.
Ironically having a martial arts symbol to represent himself, Seth is one of the least honorable characters in Street Fighter, with his ability to absorb other fighters, he copies their abilities, skills, and even iconic attacks such as the Shoryuken and without even training for them at all.
Seth has a mad lust for power, doing anything what so ever in order to gain it, even so much as to torture, such as when he tortured Dan Hibiki for the Satsui no Hado. He does not even care what people think of his methods, because Seth believes that it does not matter what humans think is evil. Power is all that is truly important to him.
Seth is the 15th of 26 enhanced beings that use data collected from the world warriors to create a deadly style of mixed martial arts. Seth claims to be superior as a result of his humanity while the others are merely puppets. His storyline indicates that he plans to control the remnants of Shadaloo through S.I.N after Bison's apparent death at the hands of Akuma in Street Fighter II. He also attempts to manipulate Juri Han, a woman who possesses a bionic eye he created. She confronts him and unexpectedly offers to work for him, to which he agrees. He hosts a World Warrior tournament in hopes of luring Ryu to complete his BLECE project, but is dismayed at reports that Bison has once again returned from death. Bison finally encounters Seth and defeats him in combat, and afterwards tells him that in fact everything that has happened has gone according to Bison's plan. After Bison leaves, Juri tells Seth that she intentionally pitted the two against each other, but is disappointed that Seth was not more of a challenge for Bison. Afterwards, Ryu would encounter another Seth and defeat him and destroy the BLECE machine. Bison commands the remaining copies of Seth and they wreak havoc on the fighters in and around the S.I.N. compound, as many of the characters' endings depict them defeating a version of Seth.
Project X Zone
Seth makes an appearance in Project X Zone. He is one of the boss characters.