Sasuke Uchiha has one of the most well-rounded and plotted character arcs in Naruto. From the very beginning of the series, he’s set up as a serious, brooding child, out for vengeance against his brother, and his attempts to become stronger all center on this one goal.
The careful build-up of interactions and battles with other characters adds to his frustration over his own lack of strength until he eventually seeks out power from Orochimaru, who offers it as long as Sasuke abandons his village and eventually gives over his body for Orochimaru’s use. Many characters whose influence on Sasuke eventually leads to this point, even if, ultimately, he is responsible for his own choices.
10 When Haku Nearly Kills Him
This is likely the first moment that showcases a source for Sasuke’s feelings of inadequacy. He activates his Sharingan for the first time here, and it should be a big moment in which he’s able to win the battle because of that. Instead, he very nearly dies trying to save Naruto, and in his rage and grief, Naruto loses control and attacks Haku. Considering Naruto is still pretty much an unsuccessful goof in battle at this point in the series, this must be a blow to Sasuke’s ego.
9 When Rock Lee Soundly Defeats Him During The Chunin Exams
Rock Lee challenges Sasuke to a fight before they enter the Chunin Exams because Sasuke is the most promising ninja of his class, and because Lee is interested in Sakura and wants to fight for a right to her love, as archaic as that is. Sasuke accepts the challenge, expecting that his Sharingan will make someone like Lee easy to defeat. But he doesn’t expect that Lee will be so much faster than Sasuke is physically able to keep up with, regardless of whether he can see his movements coming.
8 When Naruto Fights Against Orochimaru
When Orochimaru finds Team 7 during the Chunin Exams, he is looking for Sasuke. But Sasuke is so petrified by the vast strength and size of Orochimaru and his snake jutsu that all he wants to do is run away.
This enrages Naruto, enough for him to release some of the Nine-Tails’ chakra, and he single-handedly fights Orochimaru, literally putting Sasuke to shame over his own fear. Naruto punches Sasuke for good measure to make sure he knows how angry he is at him for being afraid.
7 When Orochimaru Puts The Curse Mark On Sasuke
Orochimaru is, of course, one of the major contributors to Sasuke’s defection, since he puts the idea in Sasuke’s head in the first place. After Sasuke puts up a pretty good fight against him in the Chunin Exams, Orochimaru puts the Curse Mark on him, introducing him to a whole new level of power he hasn’t even dreamed of yet. He doesn’t know at this point that that power comes at a price; he knows that he might need it to defeat Itachi.
6 When Kabuto Helps Team 7 During The Chunin Exam
Kabuto is working for Orochimaru from the moment viewers see him in the series, though they and Team 7 don’t know that yet. One of the sneakier things he does in this regard is positioning the team to finish the second part of the exam to shows Naruto’s chakra strength and stamina. Sasuke notes how much stronger Naruto has gotten at this point. It makes him more determined to become stronger, and he acknowledges Naruto as a potential rival, which leads to his ultimate resentment of him.
5 When He Fights Gaara And He Almost Defeats Him
Sasuke is meant to fight Gaara in the Chunin Exams finals, but the match is interrupted by the Sound and Sand ninja infiltrating and attacking the Hidden Leaf village. Sasuke pursues Gaara in the hopes of finishing their fight, but even with two attempts at the Chidori, he’s not able to put Gaara away. It’s a crushing blow to Sasuke, who has been training incredibly hard in an attempt to grow stronger just for this match.
4 When Naruto Defeats Gaara
After Sasuke tries and fails to take Gaara down, he insists on Naruto taking Sakura and getting to safety. Simultaneously, Sasuke sacrifices himself to hold Gaara back, knowing he can’t beat him. Unfortunately for Sasuke, Naruto is pretty sure he can beat him, and he isn’t going to let Sasuke be the only one to defend their village and Sakura. It’s the first throw-down, drag-out fight Naruto participates in, and the first time Sasuke sees the results of Naruto’s training, which greatly outpaces his own.
3 When He Tries To Fight Itachi And He Calls Him "Too Weak"
There are many things about Itachi’s return to Konoha that send Sasuke off the deep end. Of course, the first is that he’s not remotely interested in Sasuke, and he’s actually come to abduct Naruto, which only adds to Sasuke’s resentment of his friend.
The second is that when he actually tries to fight his brother, Sasuke is soundly defeated (leading to a popular meme image), even with the Chidori's power. Realizing just how far he has to go to measure up to his brother is a huge wake-up call.
2 When Naruto Uses The Rasengan During The Rooftop Fight
When Sasuke challenges Naruto to their long-awaited fight on the Konoha Hospital's rooftop, he does so out of jealousy and frustration, determined to prove to himself at least that Naruto isn’t stronger than him. Of course, the opposite happens, and when the Chidori and the Rasengan go up against one another, each having destroyed a water tower, it’s clear how much more powerful Naruto’s Rasengan is since it blows out the back of the tower completely. This fuels Sasuke’s frustration with his own lack of progress.
1 When The Sound Four Attack Sasuke
Right after this battle with Naruto, which ends without a winner, except that for all intents and purposes, Sasuke has lost, the Sound Four find Sasuke to bring him back with them to Orochimaru. They fight, with both Sasuke and the Sound Four using their Curse Marks, showing how much stronger the Sound Four are in their training with them. This encourages Sasuke to seek out Orochimaru even more now that he has a tangible example of his training, and it’s the last straw before he leaves.