Father’s Day - Season 1
Rose Tyler: So it’s OK when *you* go to other times, and *you* save people’s lives, but not when it’s me saving my dad.
The Doctor: I know what I’m doing; you don’t. Two sets of us being there made that a vulnerable point.
Rose Tyler: But he’s alive!
The Doctor: My entire planet died, my whole family. Do you think it never occurred to me to go back and save them?
Rose Tyler: But it’s not like I changed history. Not much. I mean, he’s never going to be a world leader. He’s not gonna… start World War III or anything.
The Doctor: Rose, there’s a man alive in the world who wasn’t alive before. An ordinary man: that’s the most important thing in creation. The whole world’s different because he’s alive!
This is what bothers me so much about the anniversary, this was important, it wasn’t that easy to rewrite time, there were rules and consequences. I miss nine too.