MB is an AI in Metroid: Other M
developed by the research staff on board the Bottle Ship
. Her design was based on that of Mother Brain
, the bio-mechanical computer that used telepathy to control the Space Pirates
. The purpose behind MB was similar in nature, as she was initially intended to control a special forces unit patterned after the Space Pirates, with cybernetically enhanced Zebesians
at its core.
However, this initial project was put aside in favor of a new objective. The development of Metroids
as bioweapons. For the project to succeed, it was theorized that the Metroids needed to recognize the form of another living being as a parent so that a proper bond could form. To this end, an android body in the form of a young woman was constructed to house the AI.
The experiment proved a success, and MB formed a bond with the research team's first cloned Metroid baby; a bond similar in nature to the one shared between bounty hunter Samus Aran
and the Metroid hatchling
she discovered on SR388
Over time, MB became a valuable asset to the research team. Intelligent and a quick learner, she was able to contribute a great deal to the scientists' findings. The head researcher, Madeline Bergman
, took a special interest in MB and treated her as a daughter, christening the android "Melissa Bergman."
MB's standing with the research team began to sour as her development progressed. After her initial contact with the Metroids, she started to develop a greater sense of self and emotional qualities likely due to the mother-like bond that they saw in her. As MB's views dissented more and more against the research staff, the Bottle Ship's scientists felt that something had to be done and chose to forcibly alter MB's personality to make her more cooperative.
As the scientists took her away to perform the procedure, MB pleaded with Madeline for help, and took the doctor's lack of assistance as a betrayal of the deep trust she had placed in her. Acting initially out of self-preservation, MB mounted a resistance against the scientists and used her telepathy to drive the research specimens on board the Bottle Ship wild. Once she had asserted control over the ship, she began plotting a plan of attack against the Galactic Federation
that had tried to use her; the unfreezable Metroids kept in Sector 0 of the Bottle Ship became an integral part of her plan and her intended primary weapon.
Madeline, in hiding, sent out a high priority distress signal code-named "Baby's Cry" in order to attract help as soon as possible. Two parties responded; Samus Aran, and a squad of Galactic Federation soldiers under Adam Malkovich
. Knowing that these newcomers were a major threat to her plans, MB went into hiding. Her alarm increased when she witnessed one of the members of Malkovich's squad murder another, and in her initial meeting with Samus, she informs the bounty hunter that the GF sent the soldiers to kill all of the survivors rather than rescue them. Her claim is backed up when a figure wearing Federation armor attempts to do both her and Samus in with heavy-lifting equipment.
By their second encounter, MB has identified Samus as the greatest threat to her plan. She formally introduces herself to the bounty hunter as "Madeline Bergman" and pretends to be the head researcher. She then feeds Samus information about the Metroids in Sector 0, and how they're controlled by an AI called MB, all in the hopes that Samus would fall for her trap and die at the hands of the genetically modified Metroids housed in that part of the ship.
Samus, however, is stopped by Adam, who convinces her to return to the Bioweapons Research Center in order to locate a survivor that had been detected in one of the lab's rooms. Upon returning to the lab, Samus locates and makes contact with the real Madeline Bergman, who then informs her that the impostor she met earlier was in fact MB.
After Samus locates Madeline, MB appears and threatens the pair with a freeze gun. Madeline pleads with MB to stand down, and for a brief moment, the android feels the affection that she has for her "mother." However, the scene is interrupted by the presence of Galactic Federation soldiers that had boarded the ship. MB knocks Madeline out of the path of a freeze gun blast and is temporarily frozen as the soldiers move in on Madeline and Samus. She quickly thaws, and once free throws her freeze gun to Madeline.
Before the Galactic Federation soldiers have a chance to retaliate, MB makes her final stand and uses her telepathy to summon powerful creatures to her aid. In the chaos, the Federation soldiers become distracted, and Samus manages to clear a path between both her and Madeline and MB. Madeline then uses the freeze gun to freeze MB once more. With the telepathic threat neutralized, the Federation soldiers turn their guns on MB, killing her.