User blog comment:B214/Question and Answers 6/@comment-168.28.156.47-20161109211610/@comment-10330822-20161110013648

The Khaos Brigade is the answer to the Three Factions' alliance. The Old Satan Faction existed before it did. Grayfia belonged to it before the story, and she defected to join Sirzechs' forces. In fact, it is stated that their star-crossed love affair is very popular among female devils.