A Single Eternity

Everybody knows that everybody dies. At least that's how it is for most people. This is not the case for Captain Jack Harkness. He is the man who can't die. Jack thinks that he will have to watch everyone grow old around him. What he doesn't know is that she is just like him, going through time with different names and different lives. Both think they're alone, who knows what can happen in a single eternity?