Anton-044 (also known as Blue-Four) was conscripted into the SPARTAN-II Program in 2517, when he was singled out as a physically and intellectually superior child by Dr. Halsey. He was replaced by a flash clone and abducted. He was then taken to Reach where he was trained along with the rest of the Spartans by Chief Petty Officer Franklin Mendez and Déjà. During one training exercise he and the other Spartans went to Coral and lived on their own for a few days. Anton found this particularly fun because he enjoyed beaches.
In 2552 he was briefly aboard the UNSC Pillar of Autumn when the Fall of Reach began. He was then assigned as Red-Twenty One, part of Fred's team. As the group descended to the surface of Reach, their Pelican, Bravo 001, was shot down. The Spartans were forced to jump from the vessel before it crashed.
Anton then met up with the rest of the Spartans at ODG Facility A-331. He was then assigned to lead "Team Gamma," along with Li-008 and Grace-093, they were sent by Fred to evacuate Vice Admiral Danforth Whitcomb. Though they were successful in picking up the Admiral, they were unable to meet up with "Delta" and "Alpha" teams due to Covenant activity.
They then retreated to Camp Independence for three weeks where they broadcast Oly Oly Oxen Free on the UNSC E-Band until it was picked up by John-117 and Cortana aboard the Ascendant Justice. Cortana then sent a return signal. Anton subsequently went out to meet John. Anton was the first Spartan John had met since the fall of Reach. He then listened to John's story of the events of Installation 04.
He then assisted John when they rescued the survivors of "Delta" and "Alpha" Teams, in the Forerunner Caves beneath the remains of CASTLE Base. Together, they all retreated to the Ascendant Justice/Gettysburg aboard a captured Spirit.
The group tried to initiate a Slipspace jump, but the Forerunner Crystal artifact found by Fred's team created an anomalous Slipspace bubble in which the ship was trapped. In the rift a group of Elites who had survived Cortana's takeover of the ship sabotaged the main power conduit.
When there, they were ambushed by several Elites. Anton posted on top of the Dropship to provide cover. As the conduit was repaired, a large globule of rogue plasma struck the dropship, destroying its cockpit. Anton, Li, and Polaski went missing in this event. He is listed as MIA. It is most likely that he was flash-vaporized by the extreme heat, as the Elites were.
- Halo: First Strike (First appearance)