A lonely road indeed, and this fine fic captures exactly why. I like the way you take us inside the characters and then pull back to show us how they look from the outside: "the landlord," "the potions master." They become types as well as individuals, so we can see what war does to people in general. I like how the end circles back to the beginning -- no exit for any of them, really, but especially Snape. Your prose is so evocative; I can feel their desperation and loneliness like a palpable thing.
Snape/Aberforth is an unusual pairing, but it's one I'm very fond of, and I'm always glad to be able to add another strong SS/AD to my keeper file.