The Time Traveler's Wife

One of my favorite time travel stories is actually a Deep Space Nine episode where Captain Sisko is sent back in time to Earth before the civil war. The Doctor Who episode that I still can't remember the name of the idea is that there are two times streams running parallel to each other and Amy gets stuck in one that's running faster. It's this very, very tightly contained story that she spends 40 years of her life waiting for them to rescue her. And when they rescue her, there's this, the moral dilemma in there is do they go back and rescue the Amy 40 years ago, which means that this Amy's life didn't happen? Or do they try to rescue this