Jūgo and Sasuke Uchiha
Jūgo himself didn't want to kill anyone. Jūgo's fits of rage are random, and thus, the reason why he willingly remains confined. The only reason he agreed to go with Sasuke is because he views Sasuke as the only person capable of preventing him from killing people while enraged, by the means of killer intent or the Sharingan. Before Sasuke, it was Kimimaro who kept Jūgo in check, and as Kimimaro was the only person Jūgo came into any contact with, the two grew close. After hearing that Kimimaro sacrificed his life to deliver Sasuke to Orochimaru, Jūgo believes that Kimimaro's spirit continues to live on in Sasuke.