Fire Watch, originally called Clean Killer, was a male Sphinxian treecat and a scout of the Mossy Tree Clan.

He had a sister named Silver Claw, who mated into the Black Rock Clan. She was killed along with the rest of the clan when their nesting grounds were hit by debris from HMSS Vulcan during the Mesan Operation Oyster Bay.

Clean Killer was actually in telepathic communication with his sister at the time, and was haunted by the memory. His physical wounds had healed, but learning to deal with the mental pain required far more time as well as help from Heart Singer, his clan's mind-healer.

When the elders of the treecat race decided to actively combat the Mesan Alignment by posting 'cat protectors with important human leaders, Clean Killer was among the first to volunteer. In late 1922 PD, he was assigned as bodyguard of the captured mercenary and intelligence asset Damien Harahap, in part so he could dispose of him with deadly force if he turned out to be a traitor. However, immediately upon meeting Harahap face-to-face, Clean Killer bonded with him. (HH14)