Every Major Gotham Villain Ranked From Worst To Best
Firefly is introduced as the beaten-down half-sister of a criminal family who once enveloped into their schemes, is burned by the chemicals they're using to start huge fires. She decides to start making a fire-proof suit so she doesn't get burnt again.
Her suit is melted to her body during a fight with Gordon and she's taken to Doctor Hugo Strange at Indian Hill to be experimented on. Once she's revived she turns completely maniacal during the fourth season, even going as far to claim an area of Gotham for herself and her gang.
The last time the show uses her is when she's spraying her flamethrower in the air and yelling to herself.