Mr. Fixx was Derek Powers' personal assistant and bodyguard. He was a ruthless brute deprived of any sense of morality or mercy.
Little is known about Mr. Fixx's past. He was not very talkative, but he was very threatening nonetheless. The scar under his blind left eye indicated that he had had previous physical confrontations.
Mr. Fixx was trusted with various tasks, including the most illicit errands. He could serve both as his chauffeur and as Derek's brawn. He personally murdered Warren McGinnis, making it look like an unprovoked attack by a gang of Jokerz. He also assured Powers that he wouldn't hesitate in killing young Terry McGinnis, should he interfere.
Mr. Fixx was also in charge of supervising the shipment of the nerve gas canisters to Vilmos Egans. When Batman showed up, Mr. Fixx took off with the cargo. Batman went in his pursue and broke in the hovercraft. Mr. Fixx had had activated the auto pilot, and sneaked up on Batman and engaged him with electrical brass knuckles. Fixx even complimented Batman's strength, but mocked his intent to carry the legendary hero's mantle. At this point Terry assured him he was the real deal, and slugged him hard, causing Mr. Fixx to collide with the craft's controls. The ship spun out of control and crashed in Gotham's bay, seemingly drowning Mr. Fixx together with the nerve gas vials.