Doctor Who: 10 Moments In NuWho That Made Us Cry
3. The Girl Who Waited
When Eleven, Amy and Rory visit a resort planet infected by a plague, they are accidentally separated, with Amy ending up in a different timestream. Stranded in the other timeline, Amy is alone. She explores and learns to fend for herself.
When the Doctor and Rory find their way into this timestream, Rory is on his own because the plague affects beings with two hearts, so the Doctor has to guide Rory from the TARDIS. When he finally meets up with Amy, decades have passed. She says she has been stranded for 36 years and has become embittered by her experience.
This future Amy is a cold-hearted, cynical person. Meanwhile past Amy runs the risk of turning into this bitter person. Past Amy and future Amy can speak across the timestreams through a time-glass, and both of them discuss their love of Rory being the thing that can get them through anything.
Fortunately, the Doctor has a clever plan to bring past Amy into the future. This leaves them with an enormous problem; two Amys. The group fight their way back to the TARDIS, but past Amy is knocked unconscious. Rory carries her the rest of the way. As Rory enters the TARDIS, the Doctor slams the door shut on older Amy, leaving her locked outside.