Juugo is the largest member of "Snake." He is mentally unstable, sporadically fluctuating between a bloodthirsty and a docile personality. While in the former mindset, Jugo attacks anyone around him with the intention to kill, sometimes determining which gender he will kill first during conversations with himself. It is because of this uncontrollable drive for blood that Jugo, while docile, consents to being confined since he doesn't want to hurt anyone. Kimimaro was able to control Jugo during his outbreaks, allowing him to assume a somewhat natural lifestyle where he viewed Kimimaro as a friend. After hearing that Kimimaro sacrificed his life for Sasuke, Jugo agrees to accompany him since he believes that Kimimaro's spirit continues to live on in Sasuke.
(Source From Wikipedia)
(Source From Wikipedia)
Juugo Abilities
Jugo is the source and means behind Orochimaru's development of the cursed seals. Some time in the past, Jugo purposely sought out Orochimaru to cure him of his murderous tendencies. Upon examination, Orochimaru was able to isolate enzymes in Jugo's blood that produced a unique transformation. By extracting these enzymes, Orochimaru was able to use them to produce similar, but more controlled, effects in other people. While others are confined to a single transformation, Jugo can alter his own transformation to better suit a situation, creating blades or bludgeoning objects on isolated parts of his body. Jugo is also able to understand animals, using them as scouts to help him accomplish tasks. (Source From Wikipedia)