Byron Meredith was a psychiatrist at Arkham Asylum. Known for his harsh treatments of the prisoners and his intrest in patients obsessed over the Joker, Meredith, in his later life, decided to try and manipulate these patients by founding the League of Smiles. Under his criminal name the Merrymaker, Byron wreaked havoc across Gotham City.
Working under Jeremiah Arkham at Arkham Asylum, Byron Meredith specialized in trying to treat the Joker. A married man, Byron led a happy life, though his nasty divorce left him quite bitter. Working for some time with Harleen Quinzel, Byron noticed how the Joker was able to manipulate her into insanity. Deciding to instead treat those obsessed with the Joker, Byron came up with the persona of the Merrymaker. Founding the League of Smiles, Byron helped get certain patients of Arkham released so they could later help him in crimes. After the Dollmaker cut off the face of the Joker, only Arkham staff knew that the clown prince was not dead. Using the League of Smiles, Byron was able to stage mass protests in the name of the Joker, though these protests would eventually fade away.
After the Joker returned, mass chaos erupted in Arkham and Byron assumed the role of the Merrymaker. Faking his death via dental records, Byron was gone and only the Merrymaker was left. Using the League of Smiles, the Merrymaker decided to try and kill those who had wronged him and get rich at the same time. Byron's plan did not work as the Batman caught on to his plans and eventually exposed him to the League. Following, Byron revealed him history to a fellow psychiatrist who, against Byron's wishes, had the Merrymaker locked up in Arkham and not Blackgate Penitentiary. However, Byron's days in Arkham slowly became better after being exposed to a strange chemical during Gothtopia. He began to believe he was a psychiatrist who was to attempt to cure the Batman.