Ralph Coltrane was a soldier who worked in San Pedro Overflow Camp after Miracle Day. He was present when Colin Maloney showed Dr Vera Juarez around the camp. Ralph was also present when Colin Maloney shot Vera twice, and made an attempt to calm him down but was too frightened to try. He took Colin and Vera to the Modules, not knowing what was to happen there. Ralph left Vera with Colin at the modules, where Colin had her incinerated. (TW: The Categories of Life)
When Colin returned, Ralph asked about what happened at the modules. Ralph got the truth, and panicked. Colin asked Ralph to try and cover up what had happened to her. Later, when Ralph found Colin strangling Esther Drummond, he redeemed himself by shooting Colin twice with his gun.
He told Esther he just wanted the madness to end. (TW: The Middle Men)