My goodness, this was absolutely fantastic! I'd been following this exchange, but I *never* expected anyone to write my favorite pairing, but, oh, someone did and it was marvelous! I'll try to be as coherent as I can.
It's so hard to pick my favorite bits. I loved how introspective (and angsty!) Horace was throughout the piece; it made me really feel for him. I loved how you've fleshed out his background; it's something those of us who write him have to do, and I thought it was all completely believable. And of course, the sex was so hot, I can't even put it into words. I loved how insecure Horace was and just the way the two connected. (I definitely read that scene more than once...)
This is the line that really made me melt: Albus returned the embrace, seeming to almost burrow into Horace's comforting touch. "I shall do my very best to... my love. My only love."
Also, I cried when Albus died, even though I knew it was coming; it's a testament to how well you were able to connect the reader to Horace in the story.
And of course, the end was perfect. :) The whole thing just made me all warm and fuzzy inside. Great job! Can't wait to find out who you are. :)