The central narrative twist confirms that Eduardo Pérez is indeed the legendary supervillain El Macho, who staged his dramatic death years earlier by riding a TNT-laden shark into a volcano. Operating from a subterranean fortress beneath his Mexican restaurant, Eduardo steals the PX-41 mutagen to convert Gru's kidnapped Minions into an invincible, ravenous purple mutant strike force intended for global conquest.
Dr. Nefario's brief defection to El Macho serves as a moral turning point: upon realizing that El Macho's schemes directly imperil Gru, Margo, Edith, and Agnes, Nefario's familial loyalty overrides his villainous nostalgia. He synthesizes an antidote (PX-47) by blending it into his unpalatable jelly concoction.
The film's climax features Gru and Dr. Nefario weaponizing jelly-dispensing guns to cure the Minions before Gru confronts the mutagen-infused El Macho, defeating him with Lucy's lipstick taser. In the romantic resolution, Gru rescues Lucy from the shark-rocket heading toward the volcano; the narrative concludes with their wedding after 147 dates, permanently integrating Lucy into the family unit as mother to the girls.