Priest Seto, the Egyptian incarnate of Seto Kaiba, is one of the more powerful of the Chosen Priests on the Pharaoh's court in the Memory World arc. He's the second holder of the Millennium Rod, and although he lusts for great power, he remains loyal to his Pharaoh to the very end.
Although Seto is Akhenaden's son (and thus Atem's cousin), he is raised as a commoner, and his royal birth is hidden from him out of fear for his safety. He is eventually able to become a part of the Pharaoh's guard not because of his lineage, but because of his test scores, which are the highest the court has ever seen. This high degree of intelligence has apparently carried over to his modern-day reincarnation.
As a child, he saves a girl named Kisara from a band of raiders, who then retaliate by burning down his village and killing his mother. As the raiders are about to attack him, a white dragon appears and obliterates them, leaving a strong impression in Seto's memory.
After Seto joins the Pharaoh's royal court, he decides that Bakura is too great a threat, and begins his search for a Ka that can defeat Bakura's Diabound. People could be tortured into revealing their Kas, so he decides to try rounding up and torturing criminals. This plan, he believes, would accomplish two things: finding a Ka that could destroy Diabound, and reducing the number of criminals in the Pharaoh's kingdom. During his search, Seto once again rescues Kisara, who is being stoned because of her unorthodox complexion (pale skin, white hair, blue eyes). Shaada tells him that her Ka is unusually strong, and Seto takes her back with him to the palace, where he remembers the first time they met.
Akhenaden, now possessed by Zorc Necrophades, subsequently attempts to test Kisara's power by forcing her to fight in a battle against two other Ka. Although Seto steps in to save her, the two fall into danger, causing Kisara--out of fear for Seto--to finally release her Ka (the Blue Eyes White Dragon) and save them both.
Akhenaden then orders Seto to kill Kisara and extract her Ka, claiming that the power of the white dragon can surpass the enemy and even the Pharaoh's three gods. If Seto can obtain it, Seto can become the new king. Seto refuses, and Akhenaden kidnaps him in an attempt to corrupt him with darkness. Kisara runs to save him, ultimately breaking Seto free from Akhenaden's control. Enraged, Akhenaden questions how his son could abandon the chance to rule over Egypt. Seto answers: "What is there to benefit from a world of darkness ruled by Zorc? Since I met Kisara, I realized how much of the world was dark and dry. And the solution to make this darkness disappear is through this light called love." At this point Akhenaden fires off a beam of dark energy, and Kisara dies taking the blow meant for Seto. Her Ka is then sealed by Akhenaden into a stone tablet.
Distraught, Seto attempts to kill his father, but instead his mind is taken over by Akhenaden/Zorc and he is forced to fight Pharaoh Atem. Kisara saves Seto once more by using her "light" to purge Akhenaden from his mind, making Seto the new keeper of the Blue Eyes White Dragon. Seto sheds his first tears in front of the BEWD tablet, with Kisara's dead body in his arms. Notably, this is the "vision" which appeared to Kaiba during his duel in Battle City.
After these events, Seto fights bravely by Atem's side in the battle against Zorc Necrophades using the BEWD. After Zorc is defeated, Atem says that his reign is over, and names Seto the new pharaoh. Priest Seto then creates the famous stone carving of the two of them, as a tribute to his friendship with Pharaoh Atem.
Takahashi has stated that he originally planned for the story to have further explored the relationship between Seto and Kisara (including a subplot where Seto rebels against Atem to avenge Kisara's death), but in order to meet a deadline these details had to be cut. According to the author, Seto's feelings for Kisara are the reason behind Kaiba's modern-day obsession with the Blue-Eyes White Dragon.
Birthdate: Unknown (Unknown Star Sign)
Height: See Seto Kaiba
Favorite Food: Unknown
Least Favorite Food: Unknown
Relatives: Atemu (cousin), Priest Akunadin (deceased only in original version, trapped in Shadow Realm in dub), mother (deceased, killed in fire)
Heros: Kisara and most likely his mother
Rivals: Priest Mahaado
Ka: Duos (later the Blue-Eyes White Dragon)
Deck Theme: Beatdown
Voice Actors: Eric Stuart (dub), Kenjiro Tsuda (Yu-Gi-Oh Duel Monsters).