Sasuke is 17, when he was an child he lost his clan to his brother Itachi, he slaughtered all of them in front of him. Ever since that happened he was filled with hatred and revenge, he leaved his friend's to be more powerful but doesn't regret it, since for him it was for the greater good. But he does feels lonely some times. The hatred of revenge made Sasuke a bad person, Sasuke hate his old self and having feelings, for him it just maked him weak.