Jethro was on holiday with his parents to see the planet Midnight but it all went wrong as a sinister force attacked the shuttle bus and the knocking on the walls began.
He had a morbid curiosity in everything, at first taking an almost childish delight in the shuttle bus breaking down and then in making the possessed Sky Silvestry repeat "666". Though he was a typical rebellious teenager, taking pleasure in irritating his mother, he tended to back down in response to his parents' constant criticism. This led him to eventually help the other passengers in their attempt to throw the Tenth Doctor from the shuttle rather than continuing to defend him as he had done before. Despite this Jethro showed more intelligence and was more open-minded than the rest of the passengers. (TV: Midnight)