Here was Steve Rogers, in 1944, thinking all the worst had already happened to him, when it hadn't even begun to happen, and there was nothing Jack could do to stop it.

Captain Jack Harkness runs into Steve and Bucky during WWII. When he says goodbye he assumes he'll never see them again, but is surprised when years later he runs into Steve.

Steve sucked in a breath, staring at the door in front of him. Could it be? No, it was impossible. Foolish to think. Yet he couldn't quite shake it from his mind. Jack couldn't be dead. It was impossible! After seventy years, Steve finds the trace of a man he used to know. All he has to do is open a door. Jack Harkness/Steve Rogers.

Based on a gifset I saw on tumblr. Steve meets Jack back in the 1940s.

When he first crashed into the ice, his head had been a whirlwind of regrets and missed opportunities. But the biggest of them all, the most pressing and desperate and fierce, was the fact that he'd never see Captain Jack Harkness again. It now appears that such a sentiment was unnecessary.

Captain Jack and Captain America meet twice in there lives once during World War 2 and once during Steve's time as an Avenger, Small Sherlock crossover if you know what you are looking for, No Slash rated T for Jacks Flirting Disclamer don't own either Torchwood, Captian America, or Sherlock

There're not many people who could understand what it was like to be forced into the future. It's lucky for Steve that he'd once met a man with a dazzling smile, who just happened to be sticking around for a while. Steve/Jack slash.