Mercey Island is located off the coast of Gotham County north of Gotham City. Cement tycoon Eric Mercey built a giant gothic mansion in the wooded hills of the island for his family and he. Here Mercey would entertain the creme de la creme of Gotham society. Little is known about the Mercey family or what may have caused them to leave the family manor, but the once decadent halls of Mercey Mansion had laid empty for more than a decade. Some years ago, the Joker took an interest in the mansion, perhaps because the twisted corridors echoed the "strange convolutions of his own mind". Discovering that the manor had its own theater, the Joker used it as a place to re-enact the days when he was a down on his luck comedian. His quite literally captive audience was comprised of people from his past who failed to laugh at his jokes. He executed several of his prisoners before Batman tracked him down and attacked him in the theater. Another vigilante, the revenge-driven Wilde Norton burst into the theater in the hopes of killing the Joker, but instead received a blast of concentrated Joker venom. Shortly after this incident, Jeremiah Arkham visited the island and believed that Mercey Mansion would make an excellent substitute for the recently destroyed Arkham Asylum. Before long, the mansion was converted into a hospital, and Jeremiah remained on as the lead administrator of a brand new mental health facility.
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