Short and sweet. The one thing that would have made it better is if there was some sort of flashback or something to put the reader into the emotion and situation that brought this about. Then again, I am a sucker for character interaction so of course I would say that.

I like it, but the spare feeling leave me empty at the end. Some mention of Arthur or of contingency plans in place would foreshadow what Walter had to do.

I think the line that doesn't work (for me) is this one "And in the end, his response had been unequivocal, ending both the request and his relationship with the one and only love of his life." because up until then, it felt like he was on the cusp of deciding and it had an urgency to it. After that line, and the lovely poetry, it feels like you've left out the action which would otherwise be the meat of it. If you alter it, it can remain short and sweet. Perhaps something like him remembering the lines as he walked to see Arthur? That would imply some future action that we know will end in Alucard's being sealed without feeling like we missed anything.

Absolutely beautiful, I wish it had been longer.

Nice to see you back and writing again, even if it is for something so frickin' short.