Harry was getting old, the fire that raged in him all his life was fading, sustained only by the bitter anger at a world that refused to change.
He had his friends, his family, the people who would gladly follow him into the hell he was about to unleash on the world. But what could he get out of this "glorious revolution" without her?
It was Fleur that fanned the flames of his soul, helped him control that fire, taught him that he could do more than create what would be his own funeral pyre. But she was gone now, taken by a world in need of a savior he could never hope to be. He couldn't save the world, he wasn't strong enough to do it, to tend that twisted garden into something beautiful.
All he could do it was burn it down, and hope someone could grow something from the ashes. And maybe, at the end of this damnable road, he might be able to walk the golden streets they dreamed of with her.
(A little thing born from listening to a bunch of Aviators songs, reading some Dark Lord Potter fics, and thinking about the idea of a Pyromancer!Harry)