The Doctor’s lastest companion, Rose, is the first companion of the Doctors with a fully fleshes out life story that the audience gets to see from her debut story. She, unlike other companions, has not been cut off from her family or the world she knew.
they are a cross between the oriental-style Geisha and the classic courtesan of renaissance Italy. often recognized as the highest nobility of the 'Verse
"There are advantanges to having a companion on the ship"