This Ratman (-2004) was a volunteer for the experiments by Noah Goring and eventually was mutated to a hybrid.
Day 1[]
Knowing with Mic Stone that the Dragon Clan keep the Orb Alliance Viewer in the Canton Bank, they robbed it, killed Tad Timov and stole it. Once outside again, they are spotted by another Dragon, who gave chase. The mutants killed him as well and fled but in the process the Ratman lost his fang.
Then they traveled to the Warehouse perhaps intending to leave a message indicating success for Zac West. Stone however attacked the Ratman (apparently he had promised to return the Viewer to the Orbs in exchange for a reward). He wounded him but was unable to wrest the Viewer away from him. As Mic retreated empty-handed to the Ferry Building the Ratman left a message on the table with his blood: Zac- Me hurt Me got it. Traiter Mic Me at den.
Then he went to the Rat's Den through the pipe at the Hyde Street Pier. It is possible that he is the guard sleeping there.