Summary: This new version of the Doctor is a bit of a problem for Clara.
Clara sighed; sometimes this new version of the Doctor was downright crotchety. He got annoyed at the slightest thing, had no patience, especially with people, no manners, and even less tact. Half the time she felt as though she was just following him around in order to apologise for his behaviour.
Maybe this was what happened when he didn’t regenerate until he got very old. He came back with an older body, and a brain and personality more set in its ways. The Doctor she used to know had been so much more adaptable, not to mention easier to like.