Chris (Mission of the Viyrans)

Chris was one of the partygoers on Grallista Social when the Fifth Doctor and Peri Brown visited the planet. He and Peri were at a party together when he was infected with a mutagenic virus, causing him to pass out then turn into a copy of Peri. He was cured by the Viyrans and his memories of his infection were removed. (AUDIO: Mission of the Viyrans)