Hazmat

Friendly... But not too friendly.
Hazmat used to be a firebot, he worked with firemen to save people from fire, but eventually he snapped, he killed his commanding officer, the man who built him, the two children he was in the midst of saving had to watch, but one of them became afraid, backing up until he took a tumble down the staircase into burning flames, the whereabouts of Hazmat and the child are unknown."'Tick tock, I'm on the clock...'"