Long before the Shadow Moses incident, Emma lived with her mother and her stepfather, as well as her stepbrother, Hal Emmerich. She shared a very close relationship with her brother, who called her EE. They often played childhood games like house, pretending they were a married couple. Hal, however shared an intimate relationship with Emma's mother and began to neglect his stepsister. Her stepfather eventually discovered that his wife was having an affair with his son, and drowned himself. Unfortunately, Emma attempted to rescue her stepfather and almost drowned thanks to her lack of adequate swimming abilities. While she was struggling to stay afloat in the pool, she called for her stepbrother, who was at the time sleeping with his stepmother.
After this incident, Emma became an aquaphobic and distanced herself from Hal. Eventually she and her mother left for England where her mother remarried. Just before Emma's high school graduation however, she hurt her mother's third husband, Robinson, in self defence (files state that he attempted to put the moves on her). She would go on to Oxford and follow her stepbrother, Otacon's footsteps and study advanced artificial intelligence systems. During her schooling at Oxford University, she attended a special coding event hosted by the British Secret Intelligence Service, where she met great sucess. She went on to become the leader of a cracker group that instigated the NSA signal hacking assault in January 24, 2000. After this event she was invited to join of host of intelligence agencies from all over the world.
She went on to join the NSA in 2005 with the demand that they give her information on her brother (hearing about his exploits during the Shadow Moses incident). She went on to work on the development of the G.W. AI. G.W. was apparently the NSA's plan to shift all data-gathering control into a single location in order to prevent efforts of cyber terrorism. The A.I. actually played an essential role in the S3 plan, the Patriot's plan to regulate and control information on a global scale. Two years after joining the NSA, she went on to work in Arsenal Gear (under the cover of Big Shell at the time). As the events of Metal Gear Solid 2: Sons of Liberty occurred and G.W. proceeded to go haywire, she was ordered by the Patriots to create a worm cluster in order to destroy G.W.
Metal Gear Solid 2: Sons of Liberty
During the Manhattan Incident, the protaganist Raiden is sent to rescue Emma from her captors, the terrorist group known as Dead Cell. She communicates with him through the codec and shares various anecdotes regarding her parrot (named Otacon) and the reason she wears chopsticks in hair. After helping her escape the nearly flooded portion of Big Shell (caused by Fatman and his bombs), he assists her in defeating her aquaphobia and the two arrive in the stable portion of the Big Shell. Unfortunately the two have to cross a myriad of oil pipelines in order to meet up with Otacon and Solid Snake. Raiden stays behind in order to snipe the patrolling cyphers and allow Emma safe passage through the waters surrounding the Big Shell. However, before she could cross the final stretch of pipeline, Vamp (who players previously "drowned" in a vat of heavy water) appears and fatally wounds Emma before taking a bullet in the skull courtesy of Raiden and his PSG-1. Snake carries Emma to meet her brother in Shell 1 Core, where she enforces a worm cluster, modeled after Foxdie, in an effort to destroy G.W. She then proceeds to die in her stepbrothers arms. Although she held a sense of antagonism towards Otacon, there is no doubt that she loved him (in fact it is hinted before her death that she loved Otacon romantically, but her true feelings are never expressed fully to her stepbrother).
Emma is mentioned briefly in Metal Gear Solid 4: Guns of the Patriots; after Old Snake encounters Vamp, Otacon asks Snake to kill his sister's murderer as a personal favour. Later, an upgraded version of FoxALIVE, a computer virus designed by Emma, is used to destroy the AI networks that comprise the Patriots.