Hocking, 26, self-published the trilogy about a girl who finds herself in a land of beautiful trolls before receiving a $1 million book deal on the back of her online sales.
According to Variety, Tatchell will be penning the scripts to Switched, Ascend and Torn, two of which will be combined into one film.
Speaking to The New York Times, she said about contacting the author: "I was mildly obsessed [after reading the books]. [Amanda] wrote back right away, and we immediately hit it off."
The writer was nominated for an Academy Award and a BAFTA for the South Africa-set alien apartheid film in 2010.