Doctor Who episode 625: The Twin Dilemma – Part Three (29/3/1984)
‘It’s called compassion Doctor, it’s the difference that remains between us.’ Steven Moffat did the whole ‘She cares so I don’t have to’ storyline with Peter Capaldi and I like this about the same. In principle, the idea of the Doctor going bad is workable – The Invasion of Time showed that. But the regeneration has already disrupted normality enough, and, thanks to the decision to end the season with this, there are only four episodes to establish the new reality. So, keeping the audience so uncertain about the new Doctor for so long is a risky gamble.