Doctor Who show, as the story begins anew with each companion and she undergoes more change than the Doctor. The primary companions of the Ninth and Tenth Doctors were Rose Tyler (Billie Piper), Martha Jones (Freema Agyeman), and Donna Noble (Catherine Tate) with Mickey Smith (Noel Clarke) and Jack Harkness (John Barrowman) recurring as secondary companion figures. The Eleventh Doctor became the first to travel with a married couple, Amy Pond (Karen Gillan) and Rory Williams (Arthur Darvill), whilst out-of-sync meetings with River Song (Alex Kingston) and Clara Oswald (Jenna Coleman) provided ongoing story arcs. The tenth series introduced Pearl Mackie as
The Doctor (Doctor Who) been explained. An essay in the "About Time" episode guides by Lawrence Miles and Tat Wood suggests that Time Lords are somehow exempt from the effect by their very nature. Rose Tyler is seen holding an infant version of herself in "Father's Day", with no visible energy discharge, but the contact does allow the Reapers to enter the church in which the Doctor and several others are taking refuge. While doing a live commentary on the episode at the 2006 Bristol Comic Expo, episode author Paul Cornell said that this is supposed to be due to the Blinovitch Limitation Effect,