A musical prodigy, Parish was studying to be a concert pianist when he took the gen ed biology class that would change his life. Changing his major midstream, he managed to complete his degree on time and would take two doctorates in biology and cell biology before going to work for the SGC. He was chosen as a member of the First Atlantis Expedition. Following the recovery of the Tria crew, she was almong those who requested to remain in the city.
During the Second Exodus, he was named head of Area 51's xenobiology department; the base also hired fellow former First Expedition members Rodney McKay and Rachel Biro. With their help, he was able to remove all copies of the ATA gene vaccination from Area 51 as well as several other essential basic medicines that would be hard to manufacture in Pegasus. He is wanted by the US military for espionage, treason, sedition, fraud, and grand larcony.
Additionally, he has been in a relationship with fellow Émigré Katie Brown since late 2005.