Maria Esquival is a former citizen of Madrigal. She moved to The Rubble upon its glassing by the Covenant. She introduced Jacob Keyes to The Rubble when UNSC Midsummer Night was forced to dock with it, and offered them citizenship in the Rubble. Maria is also related to Diego Esquival, a member of The Rubble's security council. During the chaos at The Rubble, Diego was shot, and Maria took his place temporarily on the Security Council.
- She may have also been close to Ignatio Delgado as she calls him "Nacho," and according to Delgado, she was the only one who knew him when he was a grubby little kid back on Madrigal.
- When Madrigal was glassed she was planning her quincieñera, a coming-of-age ceremony in Latin American culture held on a girl's fifteenth birthday. This means that she was 14 when Madrigal was glassed. Thus unless she was planning far in advance of her birthday or Madrigal was glassed late in the year there is strong possibility that she was born in 2513 rather than 2514 (as she would have turned 15 in 2528). Additionally, the quincieñera is a Roman Catholic religious ceremony which includes an affirmation of faith, implying that Maria is (or at least was) Catholic.
- Although Maria was never officially an Insurrectionist, she appears to have acquired some of her brother's Insurrectionist views.