I. LOVE. This. Lupin looking at Snape, not just looking at him but LOOKING at him, all, "Now how did I get so lucky as to be having it off with you three times a week plus Thursdays after elevenses?" And Snape all caught up in what he's doing, and the astonishing colors in this, the dancing beautiful flames and the gleam of the potions bottles in the indirect light, WOW.