So like the subject line says, in the story, after Alan dies Don moves into the house with Charlie.  At first it's genish, but slowly the relationship builds into more.  I'm pretty sure it was in Don's point of view, quite possibly with home somehow in the title.  I just read it recently but I can't think of where.  I will love forever anyone who finds it for me and convinces me I'm not crazy and that such a story indeed does exist.