Firefly as a corporate espionage agent tasked by Gotham's corrupt elite to destroy evidence of their corruption, who is then double-crossed when Batman and Jim's MCU put the squeeze on corruption and target Lyons as a suspect/potential informant, so one job he's on is sabotaged to tie up the loose end before he can be apprehended and caught, and he's left to burn from his own job but miraculously survives and turns around to wage a revenge-based war on those who betrayed him