Author Notes: Thanks to Kayt for the beta help!
They had played this game before, in the seemingly distant past. Then, of course, it had only been for fun, a sort of grown up version of hide and seek and a way to pass the occasional idle times at Hogwarts. One of them got the cloak and one was empty-handed; the former would then see how long he could stay just out of the latter's reach in an enclosed space, invisible, silently and deftly maneuvering around a room or hallway, ducking the other's outstretched fingers. If enough time passed to where either got bored, the game would end, and one would be declared King of the Round, a joke that had begun with Sirius. The tradition had been passed on faithfully to Harry, the inheritor of the essential item.
Peter had never been very good at it. Careless boy. Remus laughed slightly at that, in his head.
It was just the three of them now, the main scuffle having been diverted down the street by the appearance of the rest of the Aurors. Remus moved carefully around the figure that had its back turned to him and its wand arm outstretched. His feet, clad in shoes that had been scuffed and softened (and therefore made quiet) by their many years' service, barely made a sound on the slick cobblestones of the alley. It turned out there were uses for being poor, after all. He had lost his own wand somewhere, but it didn't matter. The fight was going in the wrong direction, and he knew that if he didn't do something to get Harry back into it, all would be lost. He would take the rat with his bare hands if need be, but somehow, he didn't think that would be necessary. In all probability, Peter would startle and kill Remus in an instant, allowing Harry, in the few seconds interval between Peter's shock and any further reaction, to avenge them all.
He didn't hear, in his preoccupied state, what Peter was saying to the person, now more man than boy, pressed to the dingy wall opposite. But it didn't matter. There was no turning back now.
He waited for the perfect moment, patiently scrutinizing the other man's every move. And suddenly, there it was. Peter turned his head after making some lengthy and undoubtedly meaningless proclamation to look up the alley in the opposite direction from where Remus was standing, invisible. Seizing his opportunity, Remus stepped between the two of them and threw off the cloak. Harry, uncommonly fast and seeing his mentor's empty hands, shouted, "REMUS!" and tossed his wand into the air over the other man's head. With the speed and agility born of his intrinsically nonhuman instincts, Remus reached out and deftly caught the wand in the time that it took Peter to whip his head back around and stare, unblinking and frozen with shock, at his former friend.
"King of the Round, Peter," Remus said, calmly and clearly. "Avada Kedavra."