User blog comment:Miskos3/Episode 274: Fairy Tail Zerø: Law, Review/@comment-4933386-20160305110824/@comment-7418318-20160306013342

Considering how she never featured before or after, she seems to be just a plot device to enable to characters (and viewers) to immediately learn that Mavis stopped aging, since it would only become apparent by itself over the course of several years.