Erica Windemere was supposedly a 14 year old girl afflicted with ALS. In reality, the name was an alias used by Barb and Toby Windemere as part of an elaborate scheme to con money out of those sympathetic to 'Erica's' situation.
The novel Through the Darkness was seemingly authored by her. It described her life story and the many difficulties she faced, including her disease and her home life. This included being threatened by her mother and passed around a rape gang.
The entire story was exposed as a hoax after the murder of Douglas Lafferty brought to light the scheme. Despite that, 'Erica' was used by Detective Robert Goren to force Christine Wilkes to admit to the murder. (CI: Faith)
Erica Windermere was probably based on the Kaycee Nicole (Swenson) hoax. It also has similarities to Jeremy "Terminator" LeRoy, who was supposedly a gay, HIV-postitive teenage boy who became famous as the author of several books, including Sarah and The Heart is Deceitful Above All Things, as well as a wide range of reviews and essays. Later, it was revealed that LeRoy was actually Laura Albert, a struggling songwriter from San Francisco who had originally created LeRoy as a means of opening up about her own childhood abuse. However, New York Magazine first suggested LeRoy was a fraud in October 2005, over three years after the episode Faith originally aired.
Erica's most direct inspiration, however, might be Anthony Godby Johnson, a supposed teenage author whose book "A Rock and a Hard Place" was a total hit and had a life full of illnesses and abuse at the hand of his biological parents, just like Erica Windermere. He's almost surely confirmed to have been the creation of the school teacher Joanna Victoria Fraginals aka Vicki Johnson, who made herself pass as Godby's foster mother.