In "Serpent Hunt" and "The Pig and the Rhino", three months after the Kraang conquered New York, a desperate Steranko and Zeck resolve to capture the mutated Karai in exchange for Shredder securing their safe departure from the city. The duo succeeded, but Shredder was livid at the revelation that Steranko was behind the theft of the Kabuto helmet and that Karai escaped when the Turtles interfered. An enraged Shredder proceed to have the duo mutated in Stockman-Fly's lab, Zeck and Steranko respectively exposed to common warthog and white rhinoceros DNA introduced to their two mutagen exposure. After made Foot Clan members against their will, the two are sent after Karai before deciding to go after the Turtles instead out of misplaced revenge. They managed to capture Donatello, Raphael, April O'Neil and Casey Jones before cornering Leonardo and Michelangelo at Coney Island, the latter serving as a distraction while coming up with their mutant names from the van they arrived in. Streanko like "Rocksteady" while Zeck was not fond of initially "Bebop", the two ultimately escaping after briefly fighting the heroes over the retro-mutagen batch Donatello had concocted. They were able to recapture Karai and deliver her to their new master. Rocksteady became the Shredder's connection to the Russian mafia, as mentioned in "Casey Jones Vs. the Underworld".