Why does Iori from king of fighters hate Kyo?

Question

Im looking for things that happened in their past.

Answer 1

Their conflict isn't a personal hatred, Iori hates Kyo due to their family backgrounds. They're both the descendants of two clans that have been feuding since they defeated Orochi in ancient times.

As taken from Iori's Wikipedia entry :

In ancient times, the Yagami clan was once known as the Yasakani; at that time, they were allied with the Kusanagi clan. In 1200 CE, with the help of the Yata clan (now known as the house of Kagura), keepers of the sacred mirror, the two clans sealed Orochi away, placing him in an eternal slumber. They accomplished this by giving Orochi eight cups of wine and when he was drunk, he was weakened with the sword of Kusanagi and sealed by the Yasakani's Magatama, their mystical and spiritual flame. He was then imprisoned within the sacred mirror of the Yata. Uniting the power of the both clans, and using the crimson flames, the two blood lines managed to seal away the Orochi's power. They assigned the Clan of the Yata to look over the seal, and both clans retired to their respective villages.

As time passed, the Yasakani, tired of living in the shadow of the Kusanagi, fell to the temptation of the power of Orochi and made a blood pact with him. This gave them greater powers, but in return, they and their descendants were forever cursed. They renamed their clan the Yagami and set out to destroy the Kusanagi with their new flames, the Magatama no Orochi. The Kusanagi declared war on the Yagami in response for this treachery, a war that has killed many clan members on both sides - much to the glee of the Orochi clan.

As a side-effect of the Orochi's curse, the flames of the Yagami have a bluish tint (more purple in color). The curse also causes each heir to die young and each mother to die in childbirth.

Answer 2

Iori And Kyo