After being dismissed from Stark Industries, Kearson DeWitt was recruited by A.I.M., who tasked him to their own Iron Man project. DeWitt revived Project P.R.O.T.E.A.N. and enhanced his soldiers with P.R.O.T.E.A.N. implants. He also enhanced himself with one, which allowed him to merge physically and mentally with Ultimo.
While raiding an A.I.M. base in search of DeWitt, War Machine faced off against a P.R.O.T.E.A.N. Hybrid. Iron Man (who remained in the hangar distracting A.I.M. Drones in an attempt to buy Rhodes time) informed him that none of his weapons would be able to kill it due to its rapid healing abilities. However, even A.I.M. were not stupid enough not to build a kill switch. Stark advised Rhodes to use the shock point energy harnessed by the base's pylon towers to defeat it. Rhodes restored power to the shock point assembly and activated it, causing it to absorb the P.R.O.T.E.A.N. Hybrid and destroy it.
Afterwards, several P.R.O.T.E.A.N. Hybrids attacked S.H.I.E.L.D.'s Helicarrier. One of them grabbed Pepper Potts and threw her from it. Stark flew down and rescued her before she reached the ocean, but due to the limited capabilities of the Mark VI armor, he was unable to fly her back up; he left her in the care of a S.H.I.E.L.D. pilot. Stark fought against the P.R.O.T.E.A.N. Hybrids and A.I.M. Drones before Rhodes arrived with a plane which Stark boarded to lead them away from the Helicarrier.
During the final battle against Ultimo, Stark entered the giant robot's body and engaged DeWitt in single combat. While Dewitt's implant provided him with metallic tentacles and defence turrets, Stark was still able to defeat him. The exoskeleton attempted to extract itself from its organic host. J.A.R.V.I.S.' biological scans showed that there was irreversible P.R.O.T.E.A.N. integration. In a last desperate attempt at survival, DeWitt grabbed Stark and began draining his life force. Stark escaped when Rhodes blew up Ultimo's head and DeWitt was killed when Fury destroyed Ultimo by crashing the Helicarrier into him.