Charles Michael Collins was an accountant who lived in Gotham Estates, a suburb of Gotham City with his wife, Bonnie, and his son, Kenny. He was best known for being an exceptionally ordinary man, until an extraordinary day turned his life upside-down.
Driving home after a particularly bad day, he reached his limit when a rude driver cut him off. Charlie caught up to the man and insulted him, only to recognize him as the Joker. Terrified, Charlie tried to escape into the woods, but Joker tracked him down. Charlie promised to do anything in exchange for his life and his family's safety. Joker decided to take him up on the offer, and a frightened Charlie wondered what it was, only to be told Joker could not think of the request on such short notice. Joker decided to make Charlie his "hobby", deciding not to call in his favor right away.
Instead, Joker kept tabs on Charlie, who shortly thereafter relocated to Springdale, Ohio and changed his name to Don Wallace.
Two years later, Charlie was aghast to receive a call from Joker, "inviting" him to travel to Gotham City. When Charlie arrived, he was just as surprised to learn what the favor was: opening a door to let Harley Quinn wheel a giant cake into a testimonial dinner for Police Commissioner James Gordon. The cake released a noxious gas which stunned everyone in the room save for Harley who wore a gas mask as well as Charlie who was provided one by her.
Unknown to Charlie, Joker sprayed the door handle with an adhesive, trapping Charlie in the room while Joker planted a bomb on Gordon. Joker intended to eradicate the entire GCPD in the explosion, as well as everyone else to include Charlie, whom he had no more use for. However, Charlie had contrived a way to call for help from Batman (albeit rather crudely considering he only had a few odd and ends to work with), who arrived in time to save the Commissioner.
Later, Charlie cornered the Joker and claimed that he was going to use a bomb from the villain's van to kill him, to make sure Joker could never threaten his family again. Caught off guard, a scared Joker yelled for Batman's help, and surrendered all the information he had gathered on Charlie and his family. As Batman took Joker into custody, Charlie revealed the joke was on him for once—the bomb was a dud—a joke which Batman seemed to appreciate.