Private Carlos Benedicto Santiago ES was a Gear soldier and Dominic Santiago's older brother, as well as a close friend of Marcus Fenix. He inspired both Marcus and Dom to join the Coalition of Ordered Governments army. Since he was a child, he was Marcus' closest friend, and later became his squadmate in the army. Carlos would fight in Dushin, on the Sarfuth border, and at Aspho Fields, where he was killed in action.