Originally an employee working for Hugh Jones, Seth Voelker was chosen to become the field leader of the Serpent Squad due to his intelligence. As a former college professor, Sidewinder proved to be a formidable foe for the Thing during his first mission with the Serpent Squad. His group managed to obtain the mystical object known as the Serpent Crown, and returned it to Jones. Sidewinder later propositioned his former teammates, along with several other snake-themed villains, to join his new organization, the Serpent Society.

As founder of the Serpent Society, Sidewinder promised its members the ability to never stay imprisoned. If they were caught by the authorities, he would simply teleport them out later that night, as he proved when he teleported Anaconda out after a battle with Captain America. Sidewinder was eventually betrayed by the majority of his allies in favor for Viper. During the invasion, Sidewinder was injured and taken to a hospital, where Viper's forces searched for him. He survived the encounter, but abandoned the Serpent Society.

Later, he aided Diamondback in her escape after she betrayed the Society, though he wanted nothing else to do with her after that. He also sprang Cobra from prison, though he was immediately taken back into authorities. Although he gave up crime, Sidewinder began stealing to pay for his daughter, Amelia's, medical bills. He was apprehended by Captain America.

Most recently, Sidewinder was seen being interviewed about his thoughts of the Thunderbolts.