Peter was born the son of Ivan Limonovich, a major in the former Soviet Union’s KGB. His mother (name unknown) died after giving birth to Peter. Ivan had in 1968 agreed to serve as a spy for the United States, and Sam Fisher’s father, an undercover case officer for the Central Intelligence Agency (CIA), was dispatched to Moscow to serve as Ivan’s controller. After two years, the CIA planned to smuggle Ivan and his son Peter out of Russia, however a gun battle with Soviet troops at the Finnish border resulted in the death of Ivan. Fisher’s father (who had become good friends with Ivan) escaped with young Peter back to the United States.
Upon returning home, the Fisher family adopted Peter and raised them alongside young Sam. Having escaped Russia at such a young age, Peter never developed an accent or learned any Russian, and subsequently developed into a "typical" American boy. Both he and Sam learned the truth about Peter's past when he turned 18.
Peter died as a result of his ongoing investigation into the disappearance of Carmen Hayes, the educated daughter of an infamous Texas oil baron. He was purposely exposed to a lethal dose of plutonium hydride-19 on a drilling platform in the Labrador Sea. When he was found floating in a life raft, he was taken to Johns Hopkins hospital, and later to the army’s Chemical Casualty Care Division (CCCD).
The severity of the radiation poisoning caused Peter intense pain. While he survived long enough to be visited by Sam, Peter died two days after his arrival at the CCCD. His body was then cremated and stored in a protected container at the Umatilla Chemical Agent Disposal Facility in Oregon.
- Peter and Sam had a three-legged cat named Pod (short for Tripod) when they were young.
- Peter would, on occasion, refer to Sam as mudack (which roughly translates to "dumb ass") whenever Sam tried his patience. It's mudak which actually means "asshole".