They are a warrior race characterised by their ruthlessness and fearlessness of death. During rehearsals for their first appearance, Kevin Lindsay , who portrayed the original Sontaran, Linx, pronounced the race's name as " son-TAR-an. Linx uses a projector to bring back human scientists from the future to fix his spacecraft. Another Sontaran named Styre appears in The Sontaran Experiment , experimenting on captured astronauts on a far future Earth.
Dorium and the Doctor meet for the first time. The War Doctor arrived at his place of work and forced him to come with him. The Doctor took him to Villengard , to help him destroy the thirteen weapons factories located there before the Dalek Fleet arrived to take control of them. The Doctor used a molecular fruit bomb to turn the factories into palm trees, and the Daleks aborted their mission.
Originally a companion to River Song, Nardole has been liberated from the body of Hydroflax and reassembled by the Doctor…somehow. Now Nardole and the Doctor are travelling together…if only they could both agree why. Nardole comes across as something of a bumbling maker of mistakes, easily distracted by seemingly trivial observations on his adventures and always full of stories and anecdotes that never quite seem to make sense. Underneath the bickering and the one-upmanship, the Doctor has to admit that after twenty-four years on Darillium with River, having Nardole around is at least better than being alone. Travelling with the Doctor and Bill, Nardole swore to help the Doctor keep his sacred oath and guard the Vault whilst remaining on Earth.
Nardole was a companion of the Twelfth Doctor. Escaping a former life of crime , which eventually made him an employee of River Song , Nardole expressed deep remorse for his actions and so attempted to make up for his illicit past. While working for Dr Song on Mendorax Dellora , he was beheaded by the body of King Hydroflax , who used him to obtain information on her whereabouts.