Hee, yes, I love their friendship (just watched 4x04, and they were so much fun in that! I love how she teases him and calls him dumbo - especially when everyone's acknowledging what a genius he is, the Doctor needs to be checked sometimes ^^) And the way he gets proud of her, and the way she takes care of him, and the way she was actually learning how to drive the TARDIS - hee~!