Very powerful story. Lupin is such an interesting and tragic figure and you've really captured his trragedy well. I cannot imagine losing all of my childhood friends in such violent or nasty ways and having to go on. The poem is quite well done as well.
Very nice one shot. I think Remus grieving is one of the most difficult thing to write, and you did it very well.
Very original (one shot of Remus are very rare indeed) and well written , with a nice style.