User blog comment:B214/Question and Answers/@comment-50.11.177.49-20130624063937/@comment-1359322-20130624070257

The Lucifuge serves under the original Satan-Lucifer. So Grayfia's family is like a kin to the Lucifer. As to why he disdain his sister maybe it's because she became the wife of the "Fake" Lucifer and servant of the Gremory.