Here's an interesting guy. Apparently a fellow warrior monk, Kinoc ended up taking a position originally intended for Auron, before he fell out of favor. In the Auron sphere, Kinoc expresses his regret and reluctance to take the position, which he feels would fit Auron better. Seems like a nice, humble guy.
Then somewhere along the line he meets Maester Seymour, and things change. When next Auron and Kinoc meet, Kinoc has Auron and his fellow guardians imprisoned and sentenced to execution. And this is in addition to the way he royally screws over Baralai, Gippal, Paine, and Nooj in X-2.
When did the change occur? Did Kinoc still think he was protecting the people of Spira? Or did he just develop a superiority complex? "Those with power use it," Auron comments. Kinoc is a prime example.
"Come out. Your sentence has been decided."
"Sentence? Don't you mean execution?"
"Really, now. What person would execute a dear friend?"
"You would."
Fellow warrior monks. Trained together. Presumably grew up together. Were they friends? Rivals? Enemies? FFX really doesn't tell us for sure.
When I try to imagine Auron as a younger man, I think he'd still have the same problems getting close to people that he has when we meet him at 35. So while he may have been friendly with, and perhaps envied by, Kinoc, I doubt they were that close. Certainly Auron has no trouble seeing that Kinoc won't help Yuna and her guardians, and is, in fact, working against them. Was this a blow to Auron, to see an old friend gone bad? After all, his trigger command in the ensuing battle with Seymour has him commenting that, despite the fact that Kinoc "went bad," he is still Auron's friend. Does he mean it? Or are these just words?
Your guess is as good as mine.