Edward Whelan was a geneticist working for Baron Zemo and Primus I (who was impersonating Arnim Zola). In an experiment with the Primus/Arnim Zola imposter, his skin became a light pinkish fur color and he ended up resembling a cannibalistic, humanoid rat. Vermin was defeated by Captain America and turned over to S.H.I.E.L.D. He escaped S.H.I.E.L.D., however, and returned to the service of Zola and Zemo. Vermin was shackled by Zemo with Captain America in a dungeon; he battled mutates, escaped, and wounded Zemo.