Seymour Guado

Seymour Guado was a Guado-human halfbreed, and a maester of Yevon.

History
Spoiler warning: Plot and/or ending details follow.

Seymour was born from a Guado leader and a human woman. This was a shock for the Guado, since Seymour was only half a Guado. Therefore, he and his mother was sent to Baaj Temple. There, Seymour's mother sacrificed her life to create a dark aeon,Anima, urging the young Seymour to gain acceptance by using Anima to defeat Sin. Seymour refused to do this, claiming she was the only one whose acceptance he needed. These events changed Seymour. Once a peaceful boy, Seymour got the taste of power through Anima, leading him on a quest for more. Finally, he returned to Guadosalam and killed his father. It's also known that Baralai was his follower.

Final Fantasy X
Seymour Guado: Seymour is first introduced in the game with Mika when the player first arrives at Luca. Later on, he tries to make Yuna marry him. When the player arrives in Macalania, the player fights Seymour, and kills him(even though he tried to use Anima to kill them). But before Yuna can send him, the Guado carry his body away.

Seymour Natus: Later on, Yuna's kidnapped by Yevon in order to marry her with an unsent Seymour. Tidus, Auron and the others come to save her, but to no avail. They get captured and almost killed. Seymour however, says that he will spare them IF Yuna marries him. However, after the marriage, Seymour orders the soldiers to kill the gang. Yuna then hurries to a edge and jumps off. She summons Valefor however, making sure that she survives to get the next aeon, Bahamut. Seymour manages to capture the gang, and throws Tidus, Wakka and Rikku in a water prison, and the rest in a maze. they however manages to escape and faces Seymour again, defeating him again.

Seymour Flux: The next time they meet Seymour, is on Mt. Gagazet, after Seymour has killed many Ronso. He believes that Sin is his ultimate source for power. The gang however, defeats him again.

Seymour Omnis: Last time thet see him again, is inside Sin. Now, Sin has absorbed Seymour, making Seymour believe that he will be the new Sin. This time around, Yuna manages to send him, leading to his death.

Quotes
(to Anima if summoned under the final showdown against him) "You would oppose me as well? So be it." "Spira is a land of suffering and sorrow, caught in a spiral of death." (To the party, prior to the battle against Seymour Flux) "Pathetic mortal. Your hope ends here, and your meaningless existance with it!"