Otto was a scientist working for Oscorp with his wife Rosalie as his assistant in creating a sun fusion device using tritium. He first meets Peter Parker when Curt Connors recommends visiting him. A disastrous experiment with tritium that Octavius uses his four-armed harness to handle results in Rosie's death and the fusion of the harness to Octavius. The arms have artificial intelligence that influence Octavius into acting irrationally, and he comes into conflict with Spider-Man when he tries to rob a bank to further his experiments. He eventually kidnaps Mary Jane to an abandoned pier warehouse where he makes another attempt to harness energy from tritium. When Spider-Man arrives, they do battle, but Octavius's original personality manages to reassert itself over his arms' A.I., and he ultimately sacrifices himself to destroy the tritium reactor before it explodes.