Following Dr. Ivo Robotnik's death and the end of the First Robotnik War, the Downunda Freedom Fighters lead a clean-up effort to repair the damage done to the environment caused by their fallen nemesis, Crocbot. One member, Duck "Bill" Platypus, found some of the badnik's remains, which activated a mind controlling diode unknowingly placed on him while he was a prisoner in the Great Crater prison camp. Bill went rogue and rallied a horde of wild duckbills behind him as they disrupted cleanup efforts and caused havoc for the community, even taking some of his old teammates prisoner. With the arrival of Sonic the Hedgehog and Tails in Downunda, the Freedom Fighters were able to successfully stamp out the revolt and free Bill, whom they discovered was actually taking orders from the dismembered Crocbot. Without a leader, the other duckbills stood down and their movement was believed to be finished.
During Sonic's absence in outer space, Dr. Eggman had made another push to control the continent of Downunda. During this campaign, Duck "Bill" Platypus came under pressure from the local platypuses to ally with the Eggman Empire and lead them once again. Unable to dissuade, Bill joined the Empire, Becoming Grandmaster of the Downunda chapter of the Dark Egg Legion. Establishing a base of operations in the Great Crater where Crocbot once managed a prison camp, Bill deliberately led the Dark Egg Legion forces poorly against his friends, the Downunda Freedom Fighters, until he could explain his seeming betrayal. In late 3237, Duck "Bill" Platypus began secretly working for Dr. Finitevus. Following the latter's instructions, the Downunda Dark Egg Legion chained Angel Island to the surface of Downunda, preventing it from floating away. At the same time, the Master Emerald was attacked by Wing Dingoes, which were ultimately repelled by Vector the Crocodile and Ray the Flying Squirrel. However, with Dr. Finitevus' help, the Downunda Dark Egg Legion managed to subdue the Downunda Freedom Fighters along with Knuckles, Vector, and Mighty, and successfully captured them. Finitevus then taunted the imprisoned heroes, revealing that the Legion-and by extension the Eggman Empire under the Iron Queen-had offered him access to the Emerald for his research in exchange for his help. Leaving to secure the Emerald, he advised Bill to send men to pursue Julie-Su and Ray. After Finitevus departed, leaving the prisoners to his allies, Bill released his old teamates and the Chaotix and explained to them that his people had pressured him into siding with Eggman, and he had done so to appease them and in hopes of thwarting Eggman's advance. Having released the Downunda Freedom Fighters and Chaotix, Bill enabled the two groups to launch a decisive attack against the Downunda Dark Egg Legion, routing their troops which forced them to withdraw from their base in the Great Crater.
Duck "Bill" Platypus
Dark Legionnaire (Platyus)