Duck "Bill" Platypus

Bill was the third Mobian to join the Downunda Freedom Fighters, joining forces with Walt Wallabee and Guru Emu while investigating the mass capture of numerous Downunda Mobians. After the prisoners were freed and the team was joined by fellow investigator Wombat Stu and mercenary Barby Koala, Bill teamed up with the others in doing battle with Crocbot, even managing to destroy one of his fortresses. Their war with him raged with little variation for some time, until Miles "Tails" Prower arrived in Downunda. With his help, the Downunda Freedom Fighters were able to destroy Crocbot's main base, and seemingly destroyed their old nemesis by knocking him into the Great Crater of Dowunda with an explosive.

Crocbot later returned with even more power, capturing Bill and his teammates with an army of Combots. While Bill was his prisoner, Crocbot fitted a microchip behind the Platypus' ear that would activate a post-hypnotic suggestion, rendering Bill his obedient servant. With the aid of Knothole Freedom Fighters Bunnie Rabbot and Antoine D'Coolette, however, Bill and the others were freed and managed to overthrow Crocbot once again, destroying his headquarters and army.

During the Dowunda Freedom Fighters' clean up efforts following their battle in the Great Crater, Bill came across Crocbot's remains, which triggered his hypnotic implant. He began expressing random fits of anger, and eventually went renegade. He recruited a horde of other platypuses to do his master's bidding, attacking the clean up site to scavenge parts while the severed torso of Crocbot remained hidden and waiting to be rebuilt. After luring them into an ambush under the pretense of a truce, Bill captured Guru Emu and Wombat Stu, prompting the DFF to send for help. Sonic the Hedgehog and Tails traveled to the crater where Crocbot had been destroyed prior, and found a slave labor camp where the duckbill army using as a site for Crocbot's new base. The Freedom Fighters managed to unearth Crocbot's remains and take him offline, removing any hypnosis from Bill and the others.

Bill and his teammates were soon faced with the tedious task of selecting a new teammate after Wombat Stu left the group to join Geoffrey St. John's new Royal Secret Service. However, a warning given by the defeated Crocbot before he was shut down came true as they were forced to confront the Bunyip, a massive and ancient creature thought to be a myth. Seeking vengeance on Crocbot for imprisoning it with a dam constructed as one of his bases, the Bunyip ended up lashing out against innocent bystanders instead. Bill and the others fought it, but proved unable to defeat the creature through force. However, they were able to reason with it thanks to Barby Koala's knowledge of its language, and in destroying the dam they allowed it to go free. Pleased with their success, the team decided not to take on a new member after all.

The Downunda Freedom Fighters, Bill and the returned Wombat Stu included, were among the many Mobians who gathered at Mobius' Southern Tundra in order to destroy the Quantum Dial weapon set there by the Xorda. Bill was among the many receivers of the aliens' broadcast of impending destruction, and thus charged valiantly into battle alongside a vast myriad of other Mobians. Following the dial's destruction and Sonic's apparent sacrifice, Bill returned home to Downunda with his friends.

Months after the Xorda's attack, Dr. Eggman made another push to gain control of Downunda. The platypus people saw this as a chance to come out on top if they worked for the Eggman Empire, and pressured Bill relentlessly to be their leader in this endeavor, as he had led them once before. Since Bill was unable to dissuade them, he swore allegiance to Eggman, becoming the Grandmaster of the Platypus Dark Egg Legion and the region's Sub-Boss. His true objective however was to secretly hamper the dictator's attempts to seize the continent, leading to his ineffective leadership of the Legion. Since he was unable to contact his teammates and let them in on his ruse, it appeared as though Bill had really betrayed the rest of his team. Despite hindering the Empire's advance through Downunda, Bill was forced to make some progress occasionally or he would have been discovered.

Bill eventually teamed up with Dr. Finitevus and used the Legion to help him capture the Downunda Freedom Fighters and Chaotix. After Finitevus left to study the Master Emerald, Bill dismissed his men, giving himself a chance to free his former comrades. He then explained what had really happened to lead them to their current situation. They agreed to continue the masquerade, "imprisoning" Bill and escaping to scatter the Legion. With Finitevus defeated and the Island released, the Freedom Fighters became even more determined to defeat the Legion-though without "crushing" Bill.