Once Upon a Different Lifetime (слэш)

The night before the final test, Harry makes Eggsy a promise: once he is a Kingsman, they will talk about their future together. Then V-Day happens, and although Harry recovers, he doesn't remember that last day he spent with Eggsy. Now Eggsy has to carry on like his heart isn't breaking every time he looks at Harry and he thinks about what they might have had. He manages to do a good job of it, though, keeping things between them strictly professional.
So then, of course, Harry remembers.