From Halopedia, the Halo wiki
Service under the UNSC
After Maria Gallardo and her sister Camila finished high school, they joined up with the UNSC.
Leave on Meridian
While Maria and Camila were often not on leave at the same time, they often spent time on Meridian, where they both taught Victor how to throw a punch, handle a knife, and shoot a gun.
List of appearances