Zach was in a relationship with a girl named Gabriella. When he was deployed to Afghanistan, she cheated on him with Vincent. Unknown to him, Vincent had also joined the army and was part of his unit. Both of them signed up for Muirfield and became Beasts and they both survived after Muirfield tried to kill their unit. At some time, he received a letter from Gabriella telling him of the affair; as a result, he killed Gabriella in revenge.
Years later, he learned that someone was killing beasts, so he decided to find and kill him first. He tracked down Catherine Chandler after catching the scent at her apartment. He attacked her and tried to get her to to tell him where the beast was, but she managed to get hold of her gun and shot at him. Zach then jumped out the window. The beast later came looking for him, and he was surprised to see that it was Vincent. He discovered that Vincent had lost his memories, so he brought him to the bar that Gabriella worked at and was successful in getting him to remember what he had done to him.
Vincent tried to reason with him, but Zach only cared about revenge and told Vincent he is going to kill the one he loves before killing him; Zach then went to Catherine's high school reunion. Vincent showed up to protect her, and a fight broke out between the beasts. As Zach turned to kill Catherine, Vincent came up behind him and snapped his neck.