This is one of my favourite quotes from the entire 48 year history of the show.

Let me explain:

The Doctor begins his exile on Earth in a very bitter mood. He’s had his freedom stripped from him and has to spend his time supervising a bunch of military idiots. But while he’d never admit it at the time, he grows to love them and their blasted ways so much that in his final moments, the TARDIS recognises that one place he has become attatched to, and takes him straight there to die. At the end of it all, he finally calls UNIT his home, because since he left Susan on Earth, 100 or so years in the future, UNIT is the cloeset thing to a family that he has had.