You know how something can be so beautiful it hurts? That's what this does to me. It's got the deep underlying sorrow that just intensifies the bittersweet leap into joy. And it fills my heart precisely because it's so gorgeously and economically drawn. The whole narrative arc has a kind of silence about it, like a breath being held. The silence in which you can hear a pin drop or a log snap in the fire. The opening panel is stunning, with its sense of perspective, its isolation and dizzying view. Old Harry is lovingly depicted, his eyes so steady and far-seeing. Or perhaps inward-looking. I love your choice of colors, autumn with a hint of winter chill, the incredible atmosphere, the warmth and detail of the woodgrain, the searing light of the fire. I love the way you use shadows. The twilit photos are happy/sad in their proof that Harry's life, far from being empty, was full of love. The moment of his death is like an expelled breath, lonely and intimate at the same time. The sparks flying from the hearth are a perfect touch, and the blackness of the panel before we see Snape's mouth gives us the half-second's visual delay we need to catch up.
And then god - God! - the fact that it's Snape who appears to lead Harry over the threshold into death - that Harry comes to Snape the same age he was when Snape died - it just squeezes my heart. I know everybody's already raved about the hands, but I have to rave some more. Snape's tapering fingers and open palm aren't merely beautiful, they're like the ultimate representation of what was missing from canon - it's the lost moment between Snape and Harry that should have happened in some form or other. How could Harry not accept that hand? And the last panel, both of them young and whole and finally, finally reconciled, is where the beauty becomes breathtaking. Because it takes death to make this possible. And it's the culmination of years of waiting. It reminds me very strongly (I hope you don't mind the comparison) of the ending of Lord of the Rings, where Frodo leaves Middle Earth and Sam marries and has a family and everything a hobbit could want - until his time comes and he can depart the Shire and follow his heart into the Western Lands. That same loss and sacrifice and sense of life being ripe and full but forever incomplete until the two can be reunited. You've caught that here.
The way Snape's hand is lit in the last panel is also lovely, and so is his possessive hold on Harry's head, the absolute concentration of their kiss - yeah, this is pretty nearly perfect. Having Snape blend into darkness just adds to the hush and mystery. Their faces in shadow imply that before the kiss is broken they may have faded entirely from view.
Part of me regrets that this story will never be written, but on the other hand it would have to be pretty fucking brilliant to compare to what you've done here. You are amazing. Thank you for a moving and remarkable piece of art.