B I O S
Seto Kaiba is one of the most complicated characters of the series.
His personality has been influenced by many events that marked him forever and changed him day by day.
In his first apparition, Kaiba stole Blue Eyes White Dragon, the most important Yugi's grand-father's card.
Kaiba couldn't know that that card will become the object of his obsession because it was already destined to him since five centuries ago, in another life. At the begin of the series, Kaiba was a totally negative character. He represents the evilness and the darkness, he was faithless even with his younger brother too, in his mind there was anything but destruction and umiliation for everyone and more, he thought to be a god.
O B S E S S I O N S
He had two obsession, two games:
The first one was Chess (that he played when he was a child) and the second one was "Magic & Wizard" (also known as "Duel Monsters"), for which he spent plenty of money in cards.
Kaiba was sure to possess the most powerful cards in the world, but when he met Yugi and his game based on "the heart of the cards", he realized the he wasn't the n.1 in this game and he became crazy for this reason. His madness and his desire to delete everyone, became his reason of life.
In fact, Kaiba's soul was victim of the darkness because of his step-father, that obliged him to study in inhumanly mode. Kaiba's heart and soul become stoney and he became totally crazy.
Anyway, he always loved his brother and he wanted to make him happy giving him a family (after their parents' death). His heart was pure and proud, and thanks to Yugi and his "Panalty Game", Seto was freed from darkness.
Kaiba was in coma for a long time, he needed to reset his soul part by part, and in order to do it, he needed to close forever with his sad past, freeing himself by his chains.
P E R S O N A L I T Y
Kaiba's real personality is a strong and unbreakble spirit, a burning and proud soul that never lose his flames. From always, duels are his passion, but now he doesn't fight for destructing the others but for protecting who is important for him, that is Mokuba, his precious little brother! After him, his company, the Kaiba Corporation.
Apparently, Seto is cool and frozen, but, truly, he has a burning heart and his personality is very marked. He easily gets angry and lost the patience. When the situation is dangerous, he enters in panic but after the first moment, he can find the best strategy in order to resolve any kind of troubles. This side of his personality is very marked beacuse he considers the "life as a card", yes, this is his philosophy.
I D E O L O G Y: "Life is like a card"
Cards are all for Seto, the Begin and the End, and he found his ideology on them.
He thinks that life is the most precious card that everyone own, and for this, nobody can throw it away. Who commits this action is a prideless duelist that deserves only to be defeated.
Kaiba explains his idea to Yugi and his friends in the Duelist Kingdom, but he shows a contraddiction because, in order to don't lose the duel against Yugi (or Mokuba would lose his life), he menaces his self-destruction.
Yugi can't allow Seto's suicide and left the win of the match to him.
Kaiba has an important lesson: "Life is the most important card but there is always someone that protect it for us".
Afterwards, during the double-duel of Battle City when he must duel together with Yugi, his eternal rival, Kaiba understands how much is important to sacrifice something in order to obtain something more important.
Now Kaiba is totally free from Gozaburo's negative influence and he becomes an affidable person, that can give something without asking something else in exchange.
Behind his stone mask, he hides a sincere and honest spirit that fight with all himself in order to reach his goals.
I N S I D E
The best side of Kaiba is that he's like a "real person", with his merits and defects. He isn't totally good or bad, he can lost the patience, make a wrong decision, make a mistake, despairs but after all, he continues to walks his way with pride and decision. It isn't simple to understand what's inside Seto's heart and thoughts, but he has something more important than cards, his brother, that represents life and the family to him.
Really, Seto never leaves his pendant with Mokuba's picture (and Mokuba does the same, with the other part of the picture, with Seto). It's like a treasure for him, and looking at it, Kaiba never forget what's important to don't lose himself again.
He considers life like a card, but day by day his ideology changes: "life becomes an eternal duel that you can play with respect and pride for your opponent, everyone he would be".