Karin

Karin is a former subordinate of Orochimaru who assisted him in his experimentations and was left in charge of one of his bases while he was away; and was also the only one loyal to Orochimaru to remain even though his current status is questionable. Sasuke Uchiha recruits her as a member of Snake. While Sasuke admits she may be troublesome, he also notes that her special abilities make her useful. She also seems to have a liking for Sasuke, implying to Sasuke that a team consisting of the two of them would be much better than one with Suigetsu or Jugo. Suigetsu noted that something once happened between her and Sasuke though what this means remains unclear, since she punches Suigetsu before he can finish his sentence. Karin's special ability allows her to track specific individuals through chakra, seen when she is able to discern that Jugo is not among a crowd of prisoners through the standard concentration pose for molding chakra. It also allows her to pick up chakra from long distances and notice changes in an individual's chakra.