Zoltán Frid

 was a vampire. When he met Priskin he was shot several times but wasn't effected by him. He infected one of Priskin's men but it didn't work properly, and spent his time trying to work out what had gone wrong. He was patient zero of the gestalt vampiric entity. As part of his plans he desired the blood of Anita Kereki to get information about Budapest. The Doctor theorised that Frid wasn't a true vampire but was a similar being. He could decided who would become like him or not. He told the Doctor that he was used in the medieval times to extract information from prisoners and was locked up so the secrets wouldn't get out. When he got radio signals he decided to become active again as there was more information for him to get. He wanted sire the Doctor and then infect the whole universe. The Doctor placed a hypnoic suggestion of Celia Soames so that when information was taken from her mind the Doctor could use it against him. The suggestion was that if Frid heard the word sunbathing he would walk in the sun and die. This happened and his victims recovered. (AUDIO: The Labyrinth of Buda Castle)