Doctor Darren Agonistes Cross was the protégé of Hank Pym who usurped his mentor as CEO of Pym Technologies and rebranded it as Cross Technologies. Cross became obsessed with the Pym Particles and using Pym's technologies to achieve success, but the constant exposure to the particles negatively affected his mind. Cross had developed the Yellowjacket Suit and intended to sell it to HYDRA and the Ten Rings but Pym and Hope van Dyne joined forces with Ant-Man who destroyed his entire research. Driven mad after losing everything he built, Cross wore the suit himself and became Yellowjacket, to get revenge by killing Ant-Man and his family. As Yellowjacket threatened Cassie Lang, he was confronted by Ant-Man, who neutralized him by shrinking him down to a sub-atomic level and destroying his suit. Trapped and heavily disfigured in the Quantum Realm, Cross was found by Kang the Conqueror, who provided him with a mechanical armor and dubbed him the Mechanized Organism Designed Only for Killing, or M.O.D.O.K. for short. Cross spent over a decade serving Kang as his sentient weapon and enforcer. Eventually, Ant-Man, his daughter and the Pym family were stranded in the realm, and M.O.D.O.K. was tasked to capture the Langs. As a revolution broke out across Axia, M.O.D.O.K. attempted to annihilate Cassie one last time before she convinced him to change sides. M.O.D.O.K. turned against his master and reconciled with his old enemies before passing away.