Months have passed since the war ended. Lives are rebuilt, what was broken is now repaired, but even in the waking world Harry cannot escape the nightmares that continue to haunt him. As he considers his future, he receives an unexpected note and sets out to discover something worth living for.
(TL;DR, Harry is big depressed. Fleur takes it on herself to show Harry exactly what his sacrifices paid for. In my head I imagine the story revolving around these mysterious notes guiding Harry to all of these places and settings where he achieved something great, only to be surprised by someone that was directly affected or saved by his actions to meet him at each one to express their gratitude.)