C'rizz first appears in the playThe Creed of the Kromon, encountering the Doctor and Charley when they entered the Eutermes zone on Bortresoye. The Doctor had been exiled to Bortresoye's universe from his own. The Eutermesans are a race of reptilian humanoids, exoskeletal, with vestigial bone structures on their heads. They also have the ability to change their skin colour, blending, like chameleons, with their surroundings. The Eutermesans are the slave force of another race, the termite-like Kromon. When C'rizz meets the Doctor and Charley, he is suffering grief from the loss of his mate, L'da, whom he had left behind when he escaped the Kromon biodome. Together with the Doctor and Charley, he returns to rescue L'da and free his people from the Kromon. He succeeds in the latter, but is forced to kill L'da, who had been transformed into a Kromon queen. Still coming to terms with what he had to do, he asks to join the Doctor and Charley as they proceeded to the next zone in search of the TARDIS and the answer to the mysteries of the universe they were in. Eventually, it is revealed that C'rizz was an adept of the Church of the Foundation, which believed that all things must die, and had murdered in its name before he met L'da and left the Church. It is also revealed that the Eutermesans are more than physical chameleons, but emotional and mental ones as well, shaping their personalities to those around them but also making them easily manipulated. When the Doctor and Charley finally manage to return to their own universe, C'rizz continues to travel with them. In Absolution, C'rizz is granted massive psychic powers on a planet that resembles Hell, eventually transforming into a physical form that Charley likens to Lucifer. The Doctor theorizes that the Eutermesans genetically engineered C'rizz to house their souls in some mad bid for immortality. C'rizz eventually gives up his new form and powers by restoring the planet and its citizens back to their original forms. This action exhausts C'rizz, who then thanks the Doctor for healing his emotional wounds and calls Charley his sister before dying. Before regenerating into the War Doctor in "The Night of the Doctor", the Eighth Doctor mentions C'rizz, marking the first time that any of the Big Finish audio series has been directly referenced in the television show.
