I have no idea why I didn't think of this sooner - and I was close to settling with a generic monster costume for her ('vampire' was already taken). Marcia is, of no surprise to anyone who knows her, a gamer. Give her Halloween and she'll take the opportunity to dress as a favorite character. Yes, Tifa's a common target for cosplayers but this works nonetheless.

Art by:  marauder6272
Marcia Jamieson by:  brunicus
Tifa Lockheart by: Square