MB, also known as Melissa Bergman, is a gynoid (female android) constructed using the intellectual data of Mother Brain. She first appears in the Cryosphere, Sector 2 of the Bottle Ship, gazing down at Samus as the latter discovers the frozen corpse of Galactic Federation 07th Platoon member Maurice Favreau, whose murder MB actually witnessed prior to Samus's arrival to the sector.
Samus tracks her to a storage facility in the sector, where she convinces MB that she means her no harm. Before MB can reply, the two are ambushed by the RB176 Ferrocrusher and are briefly separated while Samus takes down the mech. When they reunite in the Bioweapon Research Center in Sector 1 (the Biosphere), MB, revealing herself as Madeline Bergman, provides information on the cause of the distress signal received earlier. She tells Samus that the Galactic Federation had been using the facility to propagate a force of bioweapons, with Zebesians at its core. However, this plan was complicated by the presence of Ridley, who turned the various creatures aboard the facility hostile, forcing Bergman to send out the distress signal because she feared for her life. As Samus ruminates over what she has been told, Bergman's story is far from finished. She reveals that the Federation was also propagating Metroids, made possible from cellular DNA taken from Samus's Power Suit. and when Samus remarks that Mother Brain's telepathy is needed to control Metroids, Bergman reveals that she and other scientists used Mother's artificial intelligence to create an android they called MB.
As Samus leaves for Sector Zero to exterminate the Metroids and MB, the latter is confronted by an unknown assailant. Upon Samus's return, MB is gone, replaced by the corpse of James Pierce. Following a climatic encounter with a Queen Metroid, Samus meets the real Madeline Bergman, who tells her the person she met earlier was in fact MB. From Bergman, Samus learns that what MB had said earlier was true, except that the distress signal was sent not because of out-of-control specimens but because of MB's rampage. Originally created to control Space Pirate forces, MB was given a human form (she originally had a brain-like form) to enable the first experimentally-produced Metroid hatchling to recognize the android as its mother, thus guaranteeing control over the creature. Madeline used MB to better understand Metroids and was useful until she developed emotions and began asserting a sense of self, the reasons for which being unknown. This led to the decision to alter MB's programming; coincidentally, the day it was to take place was the same day Ridley became violent. Because Madeline watched MB being restrained, the latter also acted violently, tossing her captors aside like rag dolls and using her telepathy to cause a revolution against the Galactic Federation. With that, the conversation ends, and the two are confronted by MB.
MB, armed with a gun, reveals her intentions: to kill Madeline. Bergman approaches MB and tries to make amends, calling her Melissa, but she is violently pushed away. At the same instant, MB is hit by an ice shot and is frozen as Galactic Federation soldiers rush into the room, guns raised at Samus and Bergman. MB quickly thaws, and as she tosses her gun aside, she uses her telepathy to seal the room and awaken Desbrachians, a new, deadly enemy which had taken the form of the alarms above the doors. As the Federation soldiers are annihilated, she sends other creatures across the facility into an uproar. Samus fends off the beasts and locks onto the android. MB meets her demise when Bergman, yelling for everyone to stop, fires a shot from MB's gun, freezing her again (this indicates that gun may belong to Pierce). Before MB can thaw, she is bombarded by gunfire from more Federation troops. A single shot pierces the ice, and she falls to the ground, dead. The Desbrachians are deactivated, and the revolt MB started is permanently ended.
Super Smash Bros. for Wii U
- "We developed an AI program that would reproduce Mother Brain's thought processes. We called it MB." —MB (Metroid: Other M)
- "How can I trust you when your troops are willing to kill each other?" —MB (Metroid: Other M)
- "Behind closed doors, the Galactic Federation was trying to create a special forces unit composed of bioweapons. In order to make it happen, they were attempting to create an organizational structure modeled after the Space Pirates, with the Zebesians at the center." —MB (Metroid: Other M)
- "Because of a certain...presence, the life-forms became ferocious. We were no longer able to control them." —MB (Metroid: Other M)
- "By 'a certain presence,' she must have meant Ridley." —Samus Aran (Metroid: Other M)
- "I gave your suit a polish so you'd be at least somewhat presentable." —Galactic Federation scientist (Metroid: Other M)
- "MB was the artificial intelligence originally developed to regenerate and control Space Pirate special forces." —Madeline Bergman (Metroid: Other M)
- "Because we needed the first Metroid hatchling to recognize MB as its mother, she had to take on the form of a living thing. With that as our theoretical basis, we were able to create the ideal relationship with the Metroid, one that wasn't based on dominance or control." —Madeline Bergman (Metroid: Other M)
- "It's possible that her interactions with the Metroids brought it about, but we don't know for sure." —Madeline Bergman (Metroid: Other M)
- "My presence that day created a disturbing reaction within her." —Madeline Bergman (Metroid: Other M)
- "I was not wrong. The humans were foolish, and I was forced to bring judgment on them, and yet, because of you, I failed. You must understand the weight of your crime. You must pay the price for what you've done." —MB (Metroid: Other M)