Alopex was born an ordinary arctic fox outside of Fairbanks, Alaska. She proved herself deadly from an early age, serving as her pack's main hunter. She was both feared and respected by all other creatures in the area, save for a polar bear - the only being Alopex feared.
This life continued until she was captured by a group of scientists attempting an experiment to bring other animals to human-level intelligence. In Alopex's case, the experiment was a success, first granting her human intelligence and then a human-like body. She was rescued from the laboratory by the Foot Clan's leader, Shredder, and became an agent of the Foot Clan, believing it gave her life a purpose again.
In the Service of the Foot
One of her first missions consisted of playing a damsel in distress to Raphael so that she could find the Teenage Mutant Ninja Turtles' lair. Raphael quickly saw through her act, but she managed to escape. Alopex clashed with Raphael a second time when he and his brothers rescued Master Splinter from imprisonment at the hands of the Foot Clan.
Alopex played a major part in Shredder's ultimately unsuccessful plan to retrieve the Ashi no Himitsu, a tome containing the secrets of the original Foot Clan.
Although Alopex served the Foot faithfully, she still had some attachment to her old home and family. Seemingly aware of this, Shredder sent her back to Fairbanks - while he had the forest burned down as a test of loyalty. Alopex attacked Shredder, although she quickly surrendered and professed her ultimate loyalty to the Foot Clan. However, comparing Shredder to the bear that had been the bane of her existence in her earlier life, she secretly swore that she would one day kill him.
During a fight between Shredder and Master Splinter, Alopex finally attacked her master. She did not succeed in killing him, however, and was stopped by Shredder's granddaughter Karai - who up to that point had considered Alopex an ally and friend.
Leaving the Foot
Although injured, Alopex managed to survive and escape. She followed the Turtles, accompanied by April O'Neil and Casey Jones, to the home of April's parents, as they believed they were no longer safe in New York after the Foot had taken over the city's criminal underworld. Raphael was the first to notice her, and attacked her, believing her to still be allied with the Foot. Raphael's brothers managed to stop the fight, and after Alopex explained her situation, Splinter offered a truce with her. Alopex declined, saying she did not need his or his sons' help, but she remained close to their new home.
Alopex would later change her mind, and joined the Turtles as a resident of the O'Neils'. She even became friendly with her old nemesis, Raphael, but this quickly changed when a group of Foot assassins attacked the Turtles. Believing Alopex to still be loyal to the foot, Raphael attacked her, but stopped when proved to him that she was indeed no longer part of the Foot. She remained in Northampton when the Turtles, April, and Casey returned to New York.
Return to New York
Alopex received a vision from Kitsune, who told her to return to New York because she would be needed there.
After returning to the city, she came across Angel wearing an experimental armor and fighting a group of thugs. Although she did not reveal herself, she assisted Angel in the confrontation, saving her life.
Alopex later confronted Angel, revealing it was she who intervened in the fight. She also asked Angel to help her in a fight between the Turtles and Bebop and Rocksteady. The two arrived right as Rocksteady was about to deliver a lethal blow to Raphael; Alopex stopped him by slashing his face with her claws. Rocksteady managed to easily overpower both Alopex and Angel, but Pigeon Pete, a member of Old Hob's mutant army, saved them. Although Hob felt Alopex would be a good addition to his army, she declined the offer, instead becoming Angel's crime-fighting partner.
Alopex was created by Teenage Mutant Ninja Turtles creator Kevin Eastman, marking the first time he created a new TMNT character in over 15 years.