Marilyn Houston

Dr. Marilyn Houston is a Guardian who first appears in Season 4. Specializing in psychology and prosthetics, Marilyn is the patient, practical, and compassionate one of the Guardians.

Personality
Marilyn is shown to be very patient and insightful. In her first appearance, Marilyn plays therapist for Allan as he recounts the events at the research lab and losing Seal. Seeing that Allan is distraught, Marilyn tries to help him understand his emotions and explains that he shouldn't be so hard on himself. Throughout their conversation, Marilyn remains considerate of Allan's feelings.

Skill
Having acted as a scientist during her time in the ONC, Marilyn wasn't the most skilled combatant. Rather, Marilyn excels in psychology, emotional intelligence, social skills, and prosthetics. She has a strong ability to empathize with others while keeping her own emotions intact.

During her conversation with Allan in Catching Up, Marilyn delivers large amounts of compassion towards her friend and tries to get him to accept his emotions rather than feel ashamed of them. She also acknowledges Allan's bravery despite his mistakes and later encourages him to embrace his favored gender identity by calling him "Ellen".

Allan
Marilyn seems to be very close friends with Allan, as the two are shown having a very open and vulnerable conversation in Season 4. In addition to this, Marilyn seems to be the only one who knows of Allan's questioning gender identity, as she encourages him to try on a new suit of armor while briefly calling him "Ellen". This indicates that the two trust each other enough with their personal secrets.

Mickey
While the two are never shown on-screen together, Marilyn seemingly cared about Mickey, as she grows sad after Allan mentions his death.

Bartholomew
While the two are never shown on-screen together, Marilyn seemingly cared about Bart, as she grows sad after Allan mentions his supposed death.

Trivia

 * Marilyn was originally planned to have a Recon helmet. However, due to the shutdown of the Halo 3 servers in 2022, creator Intro-Mind lost access to the Recon armor and opted for the ODST helmet instead.