Viper also took over the Serpent Society with her followers, and had imprisoned and poisoned those who remained loyal to their original leader Sidewinder. Diamondback escaped with a weakened Sidewinder and sought the help of Steve Rogers, who had recently lost his Captain America identity and now went by the name The Captain. The Captain and his allies faced the Serpent Society and administered an antidote to those poisoned. ENMEY CAPTAIN AMERICA AND AVENGERS X-MEN
However, Viper had sent Copperhead, Cobra and Boomslang to spill a mutagen (based on Slither's blood) on the water supply of Washington DC, and then had the Captain fight a mutated president of the USA. The president sweated the mutagen out, and Viper tried to escape, but was captured by Cobra, who had a change of heart about betraying Sidewinder.