 Whereas in "The Simpsons", Lisa is the character most identified with knowledge and worldliness, in "Doctor Who" that character is the Doctor.The power relationship this affords the Doctor and Martha is challenged, in Martha's favour, for the first time in "42", when an alien possession leaves the Doctor "scared"; according to Agyeman, Martha "has to take control".This independence is continued in "Human Nature"/"The Family of Blood", of which Davies says "Martha is left facing the monsters alone.