"Kimahri Ronso (キマリ＝ロンゾ, Kimari-Ronzo) is a twenty-five-year-old Ronso and Yuna's first and most faithful guardian. He has known and protected her since she was a seven-year-old child. Even though he is seven feet tall he was not well accepted by the other Ronso, who view him as inferior due to his shorter stature and broken horn. Kimahri doesn't speak much, and is extremely protective of Yuna. In Kimahri's fighting class, one can see echoes of the Dragon Knights of older Final Fantasy games (due to his choice of weaponry and his Jump attack, although his Jump attack hits instantly with only a slight increase in damage, unlike most other Jumps) and of the Blue Mage character class, as well (the Lancet ability allows him to learn enemy attacks). Kimahri's Spirit Lance is his ultimate weapon, and it can be noted that spear or lance weapons have been a staple of the dragoon class for some time. Kimahri is the only character without a pre-determined course on the Sphere Grid, allowing the player freedom to choose Kimahri's abilities from the time of his initial stat growth.
The game's backstory reveals that Kimahri's guardianship of Yuna began long before she officially decided to become a summoner. After departing from Mt. Gagazet in shame ten years before the current events depicted in Final Fantasy X began, Kimahri discovered a dying Auron - who had managed to crawl all the way from the Zanarkand Ruins while wounded - outside Bevelle. Auron told Kimahri about the daughter of High Summoner Braska, Yuna, and asked him to fulfill a promise Auron had made to Braska in his stead: to remove Yuna from Bevelle and transport her to the island of Besaid, where she may grow up peacefully. Kimahri honored Auron's request and made sure that Yuna arrived at Besaid safely. When his task was completed, he prepared to depart, yet Yuna pleaded with him to remain with her, and he complied.
Kimahri's main character growth occurs when he finally returns to Mount Gagazet and is confronted by Biran and Yenke, who challenge him - and thus the player - to a 2-on-1 combat sequence as an obstacle to the player's progression through the Mt. Gagazet location. If the game player successfully wins the battle, the story depicts that Kimahri has proven his worth as a Ronso in defeating the two, and Biran is proud to see that Kimahri surpassed him which represents a major resolution to his character arc. Unfortunately, Seymour informs the party shortly thereafter that he has personally slaughtered nearly the entire Ronso tribe, with Kimahri swearing to avenge his fallen clansmen's demise while fighting the villain."
Source: Wikipedia, "Characters_of_Final_Fantasy_X_and_X-2", available under the CC-BY-SA License.