His mother, Margay Sorenson, tried to cure her son's mutation, but he eventually mutated further and not only became more powerful but also became mentally unstable. Terry turned to crime after his mother used up their money with her experiments, and took up the name Equinox. After a brief fight with Spider-Man, Equinox then went up against Human Torch and Iceman, but managed to escape. After going insane he again fought against Spider-Man, who teamed up with Wasp and Yellowjacket, and defeated Equinox with the help of Margay Sorenson and negating his powers with a thermic stabilizer that had been built in the Fantastic Four's lab.