Quite frankly I would have thought she would have been a perfect companion in your eyes for the afore mentioned reason's
. She does not love the Doctor she is a bit bemused by him a bit like that annoying older sister some folk used to have. Tells him to grow up, the long suffering look saying WILL YOU PLEASE GET TO THE POINT DOCTOR. The WHAT ARE YOU ON ABOUT and the classic GET A ROOM!
MMMMmm, you know I dont know if Catherene Tate will be a bad thing, might shake up the Doctor a bit.
I've got agree about the whole we love each other thing, but I think that it might be a good way to point to kids just because somethings different it's not necessarily bad or wrong. But it could be very bad if handled badly.
Get a DALEK Co
mpanion I say !