Sometimes two males combine their efforts in the sexual killing of women. Each brings a damaged history and personality. The combination then shows such additional features as male bravado, bonding and loyalty. In the best-known cases, one of the pair is the junior partner and the other the senior. This chapter looks at the lives of two such pairs: (1) Leonard Lake and Charles Ng and (2) the so-called Hillside Stranglers, Angelo Buono and Kenneth Bianchi. Leonard Lake was disturbed by being abandoned by his mother. Charles Ng was subject to harsh discipline. Lake, who exhibited murderous sibling rivalry, formed the senior partner of the two. They aimed to collect a population of sex slaves. Angelo Buono and Kenneth Bianchi both had disturbed backgrounds, Buono being the senior partner of the two. Bianchi was shunted around before being adopted. They sexually abused and tortured women before killing them.