|Meryl was a well-known career soldier due to her involvement in the Shadow Moses Incident of 2005, her first mission where she worked with famed mercenary Solid Snake. She was thought to be the niece of former FOXHOUND commander Roy Campbell but was later discovered to actually be his daughter.|
She was assigned to the nuclear disposal facility on Shadow Moses Island in 2005 as an emergency replacement, after several soldiers were reported missing. Following her arrival on the island, the unit involved with the exercise revolted along with members of FOXHOUND and took over the facility along with Metal Gear REX, which was secretly being developed there by ArmsTech. Though initially believed to be an unfortunate coincidence, it was later revealed that the Pentagon had deliberately assigned her to Shadow Moses Island that same day in order to force Roy Campbell to withhold vital information from Snake during the events of the Shadow Moses Incident. Meryl refused to join in with the rebellion and was taken prisoner, placed in the adjacent holding cell to the DARPA Chief Donald Anderson. Before this however, ArmsTech President Kenneth Baker gave Meryl a PAL card before undergoing a torture session by Revolver Ocelot. This PAL card could be used to activate or deactivate REX, and could only be used once. Afterwards, she managed to escape confinement and met up with Solid Snake, who had been forced out of retirement by the U.S. government in order to neutralize the terrorists, and the two eventually began working together.She managed to stay hidden by disguising herself as one of the Genome Soldiers using the clothes she stole from Johnny Sasaki, the guard who was watching her cell.