American Horror Story season 2's theme was originally very different before showrunner Ryan Murphy elected to change it. Fresh off the heels of Murder House, producers knew that the FX anthology's sophomore season had to be something as groundbreaking and spectacular as its predecessor was. As is often the case in film and television, what ultimately aired in Fall 2012 was certainly a deviation from original plans.
American Horror Story: Asylum (connected to 1984) blew audiences away with its captivating storytelling and range of complex, emotionally disturbed characters. Set in 1960s Massachusetts, Asylum's primary setting is the titular Briarcliff Manor, an institute for the criminally insane run by Jessica Lange's sacrilegious Sister Jude. Ryan Murphy based Briarcliff on the Willowbrook School, a negligent state-ed institution for intellectually disabled children which operated for 40 years before public outcry in response to its horrific conditions led to its closure in 1987.
Similarly, the original theme for American Horror Story season 2, before Asylum came to be, was one directly inspired by another grisly institution. Ryan Murphy had planned for the follow-up to the Beetlejuice-inspired Murder House to be set on Alcatraz Island, as confirmed in an interview (via EW), the home of a federal and military prison in San Francisco which is reportedly haunted. From 1934 to 1963, Alcatraz housed some of the most dangerous civilian prisoners, from Al Capone to George "Machine Gun" Kelly. Murphy had even planted a clue alluding to the original season 2 theme in a line of dialogue uttered by Murder House medium Billie Dean Howard. Ultimately, however, American Horror Story: Alcatraz was not meant to be, and Asylum was conceived instead.
The main reason why Ryan Murphy decided not to pursue Alcatraz was due to a J.J. Abrams-produced conspiracy thriller of the same name, which aired on FOX in early 2012. Canceled after only 1 season, Alcatraz focused on the institution's dangerous prisoners in an alternate sequence of events where they managed to escape in 1963. Understandably, the rule-breaking Murphy didn't want there to be two series centered around the institute airing almost back-to-back, and thus, the twisted and deranged American Horror Story: Asylum was born in its place.
Although Alcatraz would've been an interesting theme for American Horror Story to tackle, Asylum was a smash hit with audiences back in 2012 and received 17 nominations, with two wins, at the 2013 Emmy Awards. As it currently stands, Ryan Murphy is known to repeat and repurpose certain themes and tropes from earlier seasons of the franchise, so perhaps the Alcatraz idea will be revisited by Murphy somewhere down the line, especially considering that AHS still has three seasons left to go, with the chances of a further renewal high. Perhaps even the forthcoming American Horror Story season 11 will be Alcatraz-themed.