Karen Gillan has revealed that she thinks the chemistry between companion and Doctor is 'the heart' of the show, thanks to Billie Piper.
"I remember watching Billie Piper play Rose, and she's my favourite companion because I thought she was really brilliant with Chris Eccleston, and the chemistry she had with David Tennant was brilliant.
"It just made me realise how important it is in the show that the chemistry between the Doctor and companion is at the heart of the show."
However, she also said that the dynamic between Amy and the Doctor is set to change after the reveal of River Song's true indentity.
"It's going to take some twists and turns, and all relationships and the whole dynamic is going to change, after the big revelation at the end of the last half of the series. I had some fun with Alex Kingston, wth that."