The Idea: The Doctor lies to his companions, and then makes one of them kill the other one outside the TARDIS. There were two Amys that couldn't exist in the same universe; the paradoxes would be huge. Nevertheless, the Doctor had a plan, and so Rory trusted him. He was wrong to though. Whilst the Doctor knew that older Amy would have to die, he never told Rory this; the worst part though was that he made Rory kill her. He could see that Rory was conflicted between both versions of Amy - the Doctor himself declared that one of them wasn't real - and yet, he made Rory choose between them, instead of sorting out the problem himself. "You're turning me into you," Rory cried, and that's what made this ending so disturbing; the Doctor has a dark side, and he suppresses it most of the time, but this was a time when he refused to spare his companions from his mercilessness. He made a man kill his wife. It wouldn't be nearly as scary if it was any other character; it probably wouldn't be as scary if it wasn't Eleven, the bounciest, most playful incarnation. The Doctor, someone that we totally trust, and feel completely safe with, has a monster within him, but this is a moment when it was unleashed.
