The Submissive is currently available as an e-book and, after the print publication of The Submissive, which will appear in trade paperback, NAL will release simultaneous print and digital editions of the next two books in the series: The Dominant and The Training. The Dominant will bow from NAL on August 6, and The Training on October 1.
The series began, like Fifty Shades of Grey, as a story on the fan fiction Web site, fanfiction.net. Me posted the first portion of the series in early 2009--E.L James began posting her trilogy on that site in August 2009--and, NAL said, quickly began getting attention for the work, which follows the erotic relationship between a librarian and a wealthy businessman. 

According to NAL, The Submissive received 3 million views on fanfiction.net before being acquired by Red Publishing in 2012. Headline UK has also acquired the series.
NAL said the trilogy, on fanfiction.net as well as the Web site Twilighted.net (where it was also posted, for a period), received over 8.5 million views.