During Andy and Lauren's research into Fenris, it's said that they were "rumored to be part of a shadowy international organization known as the Hellfire Club". Originally in the comics, it was only the Hellfire Club's small governing Inner Circle (comprised of a few mutants) that did any super-villany, facing off against the X-Men. The club itself was publicly well known, and was more of an exclusive "members only" organization for the rich & powerful.