Board Thread:General Discussion/@comment-25926288-20161205015930/@comment-1894786-20161205025228

http://www.ew.com/article/2016/12/04/once-upon-time-robin-hood-gideon-spoilers

Looks like the Black Fairy is in fact the one who gave Snow the Dark Fairy Dust back in season 1. A&E directly call her the Dark Fairy, and they say they've been building her up for the past 6 years, when the Black Fairy's first mention was in Season 3.