Sasuke in early part 1 seemed to be a cold hearted jerk, that only cared for himself and had superiority complex. But then, little by little we started to see that he wasn't that cool cold hearted guy as he always pretended to be, he started to slowly opening his heart to Naruto and Sakura and to care for them, at the point he was willing to die protecting them from Gaara. Even Kabuto called out his bullshit and said "You're not cold hearted as you pretend to be". In fact, Sasuke himself said that he was afraid of new bonds and tried to act like this to avoid them in chapter 698.
His relationship with Naruto and Sakura are the main example of his character complexity. In the beginning of part 1, he seemed to dislike Naruto and feel superior to him. But in chapter 698 we discovered that he always admired Naruto and somewhat was jealous of his inner strength, which was something he lacked. He even compared Naruto to his brother. His relationship with Sakura is even more complex, I guess. Many people think that he never cared for her or that he was "abusive" to her, which is not truth. He thought that she was annoying in the beginning, but then started to tie up a bond with her and truly care for her, even risking his life for her sake.
At the moment he decided to leave Konoha, he couldn't accept Sakura's love neither Naruto's friendship, that's why he started to act like a jerk to them. Sasue was more than ready to sink deep into darkness to accomplish his goals, he stated this fact many times. I remember that he said during the Forest of Death arc when he woke up with the curse seal activated "I am an avenger and I must gain power even if it means to eat the devil's fruit", and he thought that bonds were a weakness to achieve this, so that's why he tries to cut his bonds and to push away the dear ones to him. During the war arc, for example, he was being very mean to Team 7, specially to Kakashi and Sakura. In chapter 680, he said that he just saved Sakura and Kakashi because they happened to be next to Naruto, which is a completely bullshit. Everyone with a shallow reading comprehension would think that he doesn't give a shit for them, which is not true, because he admitted that Team 7 was somewhat like a second family to him and in chapter 694 we discovered his goal: to bear the burden of the world's hatred. It kinda explains why he was being a jerk to them.
Sasuke's actions need a more deeper analyses. He may seems to be a jerk and cold hearted, but he isn't, his true self is the one displayed before the Uchiha massacre and in some moments during part 1. He was a loving boy, who loved his family so much that when he lost them, he became a broken person, who was afraid of love again. Few characters are so ambiguous like him, because at the same time he pretends to be cold and emotionless, all of his actions are driven by his emotions, specially love. His great love for his family, specially his brother, was what led him to do everything he did along the manga, which just prove that he is a passionate person inside, despite wearing a mask of a cold and cool person.
