Wow, this is really quite amazing. I love the balance of black and white and the contrast between sharply defined and shofter-edged objects. It seems fitting. I also love all the WWI touches: the barbed wire, the helmets, the jackets, the trenches. Despite the war raging outside, there's a strange sort of serenity around Harry and Severus.
Most of all, I love the feathers and how very many things they imply, all at the same time. Severus is certainly the ideal candidate for exploring all those meanings!