This is a muscle growth series focusing on characters from the entire universe of Sonic the Hedgehog, including the less known ones. I suggested including her, with  backyardgameboy's approval

Description
Fiona Fox was sneaking around the city of New Mobotropolis, bypassing Nicole's security measures and looking for any weakness that her boyfriend Scourge the Hedgehog and his gang could exploit in the future. She was also plotting to steal something meaningful to the Knothole Freedom Fighters, so as to give Sally and Sonic the middle finger, metaphorically.

However, she ended up in the unfortunate coincidence when she witnessed the cyan-glowing stone falling from the sky into the Castle Acorn. While she despised Ixis Naugus since her former time as the Knothole Freedom Fighter, she couldn't resist her own curiosity, and greed to her extent. She too witnessed the commotion inside the hall and was horrified at what that stone was capable of. As soon as the transformed counsellors angrily charged at Sonic and Sally who had just come in, Fiona called it quits and silently snuck away from the castle.

The red fox was holed up behind the bush nearby the plaza, where she resolved to discourage Scourge from coming here at this state, or alternatively, persuade him to get more allies to combat such abominations. However, Nicole the Holo-Lynx had somehow become corrupted by the cyan stone and began spreading the stone's powers across the city, muscularizing almost everyone. This forced her to leave immediately, wanted to avoid getting zapped, while running away from newly hostile warrior-citizens coming after her.

Fiona was able to reach the wall to escape, but Nicole immediately noticed and zapped her anyway. Now driven with new profound power, she vowed to serve Nicole and do whatever she wished, but at the same time plotted to have Scourge and the Destructix under her muscle umbrella. She also caught an eye on Sonic and Sally who also managed to escape, and so returned into the city to alert the converted warriors there.

Mobian Muscle Growth:
Speedy (Alt, NSFW) || Duck "Bill" Platypus (Alt, NSFW) || Jolt the Roadrunner (Alt, NSFW) || Razor the Shark (Alt, NSFW) || Eclipse the Darkling (NSFW) || Barby Koala (NSFW) || Walt Wallaby (Alt, NSFW) || Akhlut the Orca (Alt, NSFW) || Babylon Rogues (NSFW) || Crocbot (NSFW) || Silver the Hedgehog (NSFW) || Nicole the Holo-Lynx (Alt, NSFW) || Drago Wolf (NSFW) +Alt (NSFW) || Echo the Dolphin (NSFW) || Sealia Seal (NSFW) || Augustus the Polar Bear (NSFW) || Erma Ermine (NSFW) || Conquering Storm (Alt, NSFW) || Coral the Betta (NSFW) || Sleuth "Doggy" Dawg (NSFW) || Flip Penguin (NSFW) || Guntiver the Artic wolf (Alt. NSFW) || Queen Angelica the Anglerfish (NSFW) || Shift E. Wolf (Alt, NSFW) || Tex the Lizard (NSFW) || Fiona Fox (NSFW) + Classic (NSFW) + Payback (NSFW) || Amadeus Prower (NSFW) || Rosemary Prower (NSFW)