My dad sends me. Doctor Who character analysis sometimes and here's his latest:
11, more than any other Doctor, is the reason that River says, "Never let the Doctor see you get older." Rose, Martha, Amelia, Clara, Billie, Ryan, and Yaz are all young, all full of a sense of wonder for the things that the Doctor shows them. Donna is an adult. She first decided to become a companion because she was in a rut and wanted to run away from that. So 10 thought she would be like the the others. On their first trip, 9 showed Rose the end of the Earth. When she assumes that he is going to save the Earth, he corrected her. Stating that this is an unchangeable event. From the beginning, he trains her not to question his judgement on what he says cannot be changed. Donna was too old to fall for that and pushes back constantly. Okay, so you can't save everyone in Pompeii, then just save one person. It isn't an all or nothing proposition. He learned from that and tried to do better. Until he got too arrogant and tried to save someone he really should have let die. But then he became 11, the Doctor who forgets. The one who keeps running away more than any other. 200 years running away from Lake Silence. Years in a cloud over Victorian London. Years spent in a monastary.
If he can't save everyone, then fine. He won't save anyone.
Then he became 12, with a face to remind him of Donna's lesson.
