EVA, later known as Big Mama, was a Cold War-era female spy and a femme fatale, who fought alongside Big Boss during Operation Snake Eater posing as a KGB agent. She was actually a spy for the Chinese People's Liberation Army and was on a mission to obtain The Philosophers Legacy which she stole from Big Boss. She disappeared soon afterward. She is the surrogate mother of Solid Snake and Liquid Snake.
In 2014, EVA, now an elderly woman at the age of 78, contacted Solid Snake during his mission to terminate Liquid Ocelot. She goes under the codename "Big Mama" as the leader of a resistance group in Eastern Europe known as Paradise Lost.
Raiden later told Snake that EVA was in possession of Big Boss' corpse. Soon after, their location was discovered and PMCs were locking in on them. As EVA, members of the resistance, and Snake moved out, decoy vans were set to allow the van with Big Boss' corpse to get away. Riding with EVA on her motorcycle, Snake protects the van from PMCs in a wild chase until they crash because of Raging Raven's missile. After Snake defeats her, he tends to the injured Big Mama (oddly enough, she was injured at the same spot she had been injured during Operation Snake Eater and crashing in a similar manner) and they head for their getaway cruiser only to find Liquid Ocelot waiting for them. After Liquid beats Snake with CQC techniques and defeats Meryl's men with GW, Vamp tosses the corpse of Big Boss to Snake and EVA as it burns (since Liquid no longer needs Big Boss' DNA). EVA, at an attempt to save his body, gets burned. Snake saves her from Ocelot's gunshot but burns the left side of his face in the process.
Snake held Big Mama in his arms until the moment she died. It appeared she died from the combination of her injuries from the motorcycle crash and the burns she took in attempting to save Big Boss' body. However, it was later revealed by Big Boss that she died from the FOXDIE within Snake. In addition, she planned "Liquid's" insurrection from the beginning, together with Naomi and Ocelot himself, as part of their plan to destroy the Patriots' system and revive Big Boss.
