In the world of Naruto, the relationship between a jounin and his students is a very important one. The history of Konoha's greatest ninjas show an apparent line of inherited greatness. Hatake Kakashi, better known as the Copy Ninja, was once a student of the Fourth Hokage. He, in turn, was taught the way of the shinobi by one of the legendary sannins Jiraiya, who was himself taught by the man who would become the Third Hokage. Having traced such an esteemed lineage, it was only natural that the man already renowned for copying over a thousand jutsus would refuse to take under his tutelage just any three youngsters from the Konoha Academy.

We first see him as the soon-to-be leader/mentor of Team 7 long before we learn his name. Sniffing a stale milk carton in Naruto's kitchen apart, Kakashi makes his first appearance in the series. The Third Hokage is with him explaining the special circumstances of the three recently-made genins that would be assigned to him. Kakashi already suspects they will be a troublesome bunch and admits as much. The Third does not disagree, but ends their meeting by cryptically informing him that a certain Sasuke "of THAT Uchiha Clan" [ch03-p107] will also be on the team.

Suffice to say, the first meeting between Kakashi, Naruto, Sakura and Sasuke was a less than favorable one. "My first impression is... I don't like you." [ch04-p112] Nonetheless, he has the kids introduce themselves and tell him their likes, dislikes and dreams. While Naruto's dream to be acknowledged by becoming Hokage surprises Kakashi (given Naruto's history and sealed powers), Sasuke's ambition to resurrect his clan and kill a certain man is exactly what he suspected. The latter would be the boy Kakashi truly needed to watch.
This was confirmed during survival training the following morning, where he orders the three to try and take one of two bells from him by any means necessary. He warned that if they did not come after him seriously with killer intent, they would have no chance of stealing the bells from him. Though he easily subdued Sakura and Naruto with time (and hands) to spare to read his favorite paperback Come Come Paradise, the #1 Konoha Academy rookie and Uchiha prodigy proved to be a more troublesome opponent. The jounin is forced into actual physical combat in which Sasuke manages to get a finger on one of the bells before being pushed away. Having almost been caught offguard, Kakashi congratulates Sasuke by acknowledging his skill as being on a level a whole head higher than the other two. As expected of an Uchiha.

It is on their first mission abroad that Team 7 encounters the Devil of the Mist, the extremely dangerous missing-nin Zabuza, and Kakashi lifts his forehead protector to reveal his own secret: a scarred left eye with an activated sharingan. Sasuke is baffled - the sharingan is a physical condition that runs only in the Uchiha bloodline. What does it mean that a man such as Hatake Kakashi, his team leader, possessed the eye?

Fast forward to the Chuunin exam's elimination rounds. The first match is between Uchiha Sasuke and a member of the highly suspicious Sound ninja team. In front of all the other candidates as well as the Hokages and jounin team leaders, Sasuke beats the Sound ninja with a partial copy of Rock Lee's taijutsu technique "Lotus," renaming it "Lion Rendan." Though the curse inflicted on him by Orochimaru earlier in the examination momentarily prevented him from taking out his opponent, Sasuke wills it back long enough to finish the move and be declared the winner. Kakashi appears immediately at his side - being one of several who noticed the nearly fatal takeover of the curse on Sasuke's body - to take him away where the curse and its effects could be properly sealed. Standing amongst the crowd that had just witnessed a sample of the powerful Uchiha bloodline is the jounin Gai, who is impressed by Sasuke's move. Such a phsyically draining taijutsu, he explains, could not have been so perfectly executed with sharingan alone. "Kakashi... this boy reminds me of you when you were young." [ch68-p]

And what was the white-haired ninja like growing up? How did he come to gain the sharingan eye, supposedly exclusive only to the Uchiha bloodline? What is his connection to the fallen clan? And as a result, it's sole survivor Sasuke?

A flashback reveals that Kakashi is himself of high lineage, his father being none other than the legendary Konoha ninja known as The White Fang. However, his father had been disgraced by a crushing failed mission. Rather than see the mission through and achieve their goal, The White Fang had gone back to save the lives of his teammates. As a result, war waged on, and he came to be resented by everyone - even by the teammates which he had saved - and was put down with such hate and dishonor that he eventually took his own life. The sudden and violent loss of the once prominent figure in the village forever altered the boy's view on the shinobi way of life. He twisted his feelings towards his father, who it seemed he once hero-worshipped, to that of anger for not having followed orders and achieving the goal of the mission. "As a shinobi...sometimes it's essential to sacrifice your comrades for the sake of a mission." [ch241-p13] A prodigy in his own right, he became obsessed with following rules and mission plans to the letter, achieving the status of jounin at a very early age. During wartime, he distanced himself from the rest of his three-man team with his by-the-book seriousness. He was particularly annoyed and felt hampered by the dark-haired, over-sensitive, loud-mouthed and seemingly inferior-in-skills teammate Uchiha Obito. But when the third member of their team is kidnapped and the young Kakashi chooses to go through with the mission rather than attempt a rescue, Obito's anger is unleashed and he hits a nerve by mentioning The White Fang. "Of course, those in the ninja world who break rules and regulations are called trash... but those who don't care about their companions are even worse trash!" [ch241-p19] Having never heard anyone refer to his disgraced father as a hero, young Kakashi's heart changes and he forfeits the mission to join Obito in rescuing their comrade, the medical ninja Rin. However, his timing falls short, and though young Kakashi manages to defend Obito from a deadly attack at the enemy's hiedout, his left eye is slashed in the process. They get to Rin just as the cave hideout begins to crumble around them. Completely blind on his left side, Kakashi does not notice a huge boulder coming his way and Obito shoves him aside at the last minute - saving his life at the cost of his own. Obito's dying wish is that Kakashi accept his sharingan eye - only recently activated - as a present for being acknowledged as a great ninja.

Thus we learn of how Kakashi became one with his fallen comrade, an Uchiha, and rose in prominence over the years as the Copy Ninja of a thousand jutsus. It is also from this flashback that we learn of Kakashi's obsession with the importance of teamwork. Indirectly, the flashbacks also provide us with some striking parallels between the man and the current Uchiha prodigy, Sasuke. It seems that both had held high regard for their fathers at a very young age, only to have it construed as they grew older. Both were born geniuses with high expectations. Both suffered severe loss of not one, but several precious people in their lives. And both were severely affected by the losses, completely changing their personality and outlook on life. Their self-imposed martyrdom effectively distanced them from those who should've been closest - friends and comrades. The team chemistry of young Kakashi is also practically the same for Sasuke: Naruto is just as loud and stubborn in following his own "way of the ninja" as Obito. Both are annoyed and in awe of the respective genius ninja's skills, as well as jealous of the affections bestowed upon them by the female member of their team.

As a result of their similar childhood experiences and personalities at the time, it is perhaps Kakashi who can come closest to understanding the tormented thoughts that plague Sasuke's mind. He assigns another jounin to train Naruto temporarily during the Chuunin exams, much to the blonde's distaste, and takes Sasuke out for personal one-on-one training. For a month prior to the Chuunin elimination match, Kakashi trains Sasuke secretly in the canyons and teaches him his sole original jutsu - chidori. "Chidori is a power given to you because you found things important to you. That power is not something to be used on friends or for revenge." [ch177-p08] However, when he catches Sasuke fighting Naruto on the hospital rooftop a few months later using the technique, Kakashi decides its time to sit the Uchiha down and give him a good talking to. Make him understand that he too is no stranger to true pain and a desire for revenge. "We aren't the lucky ones, that's for sure. But we aren't the worst off. Both you and I have found precious companions." [ch177-p07] With those words, he leaves Sasuke to ponder his next move. Just as Kakashi had done all those years ago, Sasuke must face the crucial, life-altering decision: shall he choose his companions and forfeit his life's mission, or forsake his friends in order to fulfill his promise of revenge?