trying to understand why this scene keeps hurting and remembered that the doctor who donna first met was so certain of himself. and the donna who the doctor first met was so uncertain of herself. but the doctor regenerated into an old face because he was so uncertain of who he was, and this time.
this time around donna is certain enough of herself. certain enough of their friendship, that she calls him an idiot and tells him maybe this time i'll save you. and she does. she does, the same way she's always saved him from the very beginning: you need someone to stop you. and she does. she does, she makes him stop running. she gives him a home. she gives him a family, and the one adventure he couldn't have.
and she gives him a reason to keep going, too.