U joined Orochimaru some time before Sasuke did, u don't have a exact reason why u joined him, but when ppl ask u js say u got talent and those idiots back there are holding u back Sasuke arrived for the first time and everyone started warning him not to mess w u Orochimaru: Watch urself, buddy. This person is a great danger. Kabuto: they will surprise u, trust me. They are nice but if u mess w them ur dead in an instant. Kidōmaru: they are kinda smash tho- Tayuya: Kidōmaru! Sasuke: uh-