Warning: Spoilers below
Leo is a med school student proir to the events of Death Watch. Jack saves his life. He also says that he got an vaccine to the virus that was sprayed on the city not by killing someone, but that a person who had one died before he could use it. Leo then asks Jack to help him escape the town, but Jack responds by saying "I don't help people... I kill them" and then Jack runs off to the next match of the Death Games. Later in the game, Leo was revealed to have been working with the organizers of the games, and at the very end of the game he saves Jacks life. However, Jack already learned that he lied and destoys the communication device in his ear after partially chainsawing Leo. After Jack asked Leo why he used Death Match to reveal the virus, he replys by saying he couldn't resist the games, even though he got everything he wanted, such as drugs and women. Leo asks Jack to help him or he'll die, which Jack replies by stating "I don't help people..." He then chainsaws Leo, casuing him to fall to his death. Then Jack finishes by saying "I kill them".