Now Snape was head to head with Mundungus in an unfamiliar…

““Now Snape was head to head with Mundungus in an unfamiliar tavern, Mundungus’s face looking curiously blank, Snape frowning in concentration. “You will suggest to the Order of the Phoenix,” Snape murmured, “that they use decoys. Polyjuice Potion. Identical Potters. It is the only thing that might work. You will forget that I have suggested this. You will present it as your own idea. You understand?” “I understand,” murmured Mundungus, his eyes unfocused… Now Harry was flying alongside Snape on a broomstick through a clear dark night: He was accompanied by other hooded Death Eaters, and ahead were Lupin and a Harry who was really George…A Death Eater moved ahead of Snape and raised his wand, pointing it directly at Lupin’s back-- “ Sectumsempra! ” shouted Snape. But the spell, intended for the Death Eater’s wand hand, missed and hit George instead-- And next, Snape was kneeling in Sirius’s old bedroom. Tears were dripping from the end of his hooked nose as he read the old letter from Lily. The second page carried only a few words: could ever have been friends with Gellert Grindelwald. I think her mind’s going, personally! Lots of love, Lily Snape took the page bearing Lily’s signature, and her love, and tucked it inside his robes. Then he ripped in two the photograph he was also holding, so that he kept the part from which Lily laughed, throwing the portion showing James and Harry back onto the floor, under the chest of drawers…””

— J.K. Rowling