Miguel joins ZAFT to earn money for his younger brother's medical expenses. Known as the "Magic Bullet of Dusk," he pilots a customized orange GINN, reminiscent of twilight, and uses its high mobility to deliver lethal strikes. Miguel is a ZAFT ace under Rau Le Creuset's command, often displaying a headstrong and arrogant demeanor, frequently underestimating Natural opponents.
Miguel participates in transferring the asteroid base Nova to the PLANTs, despite finding it unexciting. During an Earth Forces raid, he engages Mu La Flaga. In January C.E. 71, the Nazca-class Vesalius investigates destroyed ZAFT supply bases under Le Creuset's command. While patrolling, Miguel discovers Serpent Tail mercenary Gai Murakumo as the culprit. His GINN gets damaged by Gai's custom GINN, forcing him to use a standard GINN during the Heliopolis attack on January 25.
During the Heliopolis assault in Gundam SEED, Miguel attempts to capture the GAT-X105 Strike after learning Rusty Mackenzie has been killed. Athrun Zala informs him that the Strike is piloted by an Earth Alliance soldier (Murrue Ramius), but fails to mention Kira Yamato, their childhood friend, is also inside. Miguel tells Athrun to retrieve the GAT-X303 Aegis before it gets damaged, then tries capturing the Strike himself. Murrue cannot match Miguel's skills, prompting Kira to take control of the Strike when he sees his friends nearby. Kira ultimately forces Miguel to retreat by disabling his GINN. Miguel escapes his exploding GINN just in time.
Believing a Natural was piloting the Strike, Miguel feels humiliated and vows revenge. He meets his end when Kira slices his GINN and him in half with the Strike's Schwert Gewehr, marking Kira's first kill. Ironically, this weapon would later be used by Kira to kill Nicol Amalfi.
