User blog comment:B214/Question and Answers 6/@comment-216.237.220.200-20190617112943/@comment-10330822-20190619012459

Riser made her his Bishop first because he wanted the "sister-type" in his harem/peerage. However, after he lost to Issei, Lady Phenex confiscated Ravel by trading a free bishop piece she had to Riser in return for her.

Lady Phenex had a peerage back in the day, but she is retired now. Whether she still had all her other peerage members still is unknown, but she had at least one free Bishop Piece, since she traded it for Ravel.