Ask a fan who the Doctor's wife is and you're bound to get two answers, even though he has been married quite a few times during the run of the show. River Song will be a very popular answer, as she is the most recent one to tie the knot with the Doctor. However, many astute fans will demand that the TARDIS is his true wife. But how could that be, seeing as the TARDIS is just a machine? Well, the TARDIS is actually a mix of machine and sentient being, one that developed a personality as well. Despite being sentient, it was unable to actually communicate with the Doctor... until the Series 6 classic The Doctor's Wife, that is. However, due to a personality shift, the body of Idris contained the essence of the TARDIS for a duration, during which it attempted to convey to the Doctor just how much she (yes - the TARDIS is female!) loves the Doctor, and that she hears when he calls her beautiful. Idris was also able to explain that, while she doesn't always bring the Doctor where he wants to go, she takes him to where he needs to go, and that she felt she was not only his closest and longest travelling companion, but his best friend, too. Many fans were sad when they learned she wouldn't be able to verbally communicate after her personality was rejoined with the box itself, but she was able to tell him the one thing she had always wanted to say to him. "Hello, it was so nice to meet you". This episode lets fans look back at all the times the Doctor called the TARDIS temperamental, or had a touching moment with what seemed to be just a machine, and were able to see the TARDIS as the Doctor sees her, as a beautiful creature, and his closest companion.