Seto Kaiba is one of anime's famous anti-heroes, alongside
Dragonball Z's Vegeta. Vegeta's character had more
development but he also started out with a significant
amount of character flaws. After Yami Yugi's
mind-crush on Kaiba, the character generally had a much more
mild development. Kaiba never changed who he was,
although he did adapt himself to changing circumstances and
improved himself in some ways.
Seto's personality was deep rooted in his status as a child
orphan. Gozaboru Kaiba, the CEO of a military
contractor, was looking for an intelligent heir to replace
his dead biological son Noah. Young Kaiba challenged
Gozaboru, who was visiting the orphange to donate gifts, to
a chess game and won. Gozaboru took him in as an
adoptive son on the condition that his little brother Mokuba
was rescued from the orphanage as well.
Gozaboru was much of a tyrant, forcing Seto to spend all of
his childhood studying rather than having fun. While
Seto was designing game products, Gozaboru was using them
for military weapons. Seto saw less merit in the
military because it was a team effort and preferred games
which were one versus one. Seto multiplied a small
share of the company he was given by smart investments,
combined with the Big Five (who felt under appreciated by
Gozaboru) and Mokuba, Seto took over the company and turned
it into a gaming company.
When Gozaboru was ousted from his own company, he committed
suicide (joining Noah in the virtual world). From then
on, Seto equated losing to death and the primary goal of his
life was to be a winner. His rivalry with Yugi is of
utmost importance to his character. Kazuki Takahasi
(creator of Yugioh) said that without an opponent stronger
than him to strive to beat, Kaiba's life would be without
purpose.
Kaiba does meet some of the criteria of a sociopath (he's
intelligent, lacks empathy, he has a constant need to be a
winner, he never apologized or feels shame or guilt), he
does not meet enough criteria to officially qualify.
He doesn't break the law, he isn't irresponsible, he isn't
lacking in planning skills, he isn't reckless and isn't much
of a charmer. A case could be made that he may have
been a sociopath before Yami Yugi separated the evil spirit
from him in the first episode.
However, Seto Kaiba does have a lot in common with Ayn
Rand's Objectivist philosophy. He is a wealthy
industrial, makes decisions based on logic rather than
emotions, values science over nature, is against altruism,
helps people only when it's in his self interest, strives
not to depend on others, is heavily prided on his
accomplishments, rejects belief in the supernatural
(destiny, millennium items, etc.), and is firmly against
cheating and stealing.
In his ancient Egyptian parallel, while Yugi was Pharaoh
Atem in the past life, Kaiba was Priest Seto, part of his
council. Seto, is appointed to Atem's council based on
his intelligence alone - rather than his bloodline. In
his position, he heavily punishes and tortures criminals.
He does rescue a woman named Kisara, who is being assailed
because of her uniquely blue-eyes and pale-skin. In
the fight against Yami Bakura and Zorc, she releases her
spirit forming the Blue-Eyes White Dragon (to protect Kaiba).
Kaiba is briefly brainwashed by his father Akhenadan into
battling against Yugi, but Kisara's spirit frees him and
they all work together to stop Zorc.
In Kaiba's modern incarnation, his affinity for the
Blue-Eyes White Dragon is due to his ancient past.
Initially, his rivalry with Yugi reflects the battle they
had in the past. While Yugi's character development
leans toward Yami/Atem giving him the confidence he needs,
Kaiba's development depends on him becoming less hostile and
more friendly to the Pharaoh. At the end of the
ancient battle, Atem retired as king and gave Priest Seto
the throne, as he earned it. Likewise, the end of the
anime with Atem/Yami leaving, suggests that Kaiba succeeds
the throne as King of Games.
