In Remus Lupin's Seventh Year, the first medical study on the spread of Lycanthropy was just being concluded. While Remus himself claimed indifference, Sirius Black was the first person in line for it at Flourish and Blotts, and then spent two days ignoring classes and Quidditch while he slogged through the medical terminology and scores of graphs and data that made his eyes water.

    In the end he presented Remus with some grim news. While you couldn't spread Lycanthropy by casual contact, there was another way besides biting near the full moon that the virus, and it was a virus they had finally decided, could be spread.

    Fluid exchange. Lycanthropy, as it turned out, was an STD.

    So seventeen-year-old Remus Lupin added a vow of chastity to the laundry list of self-controls he had placed on himself. Sirius, who always had read too much, nicknamed him Dugas, after the psychologist who'd diagnosed the first case of emotional depersonalization.

    This was the reason why it took Sirius three years to talk him into any kind of reluctant relationship.

    This was the reason why, when Albus Dumbledore was standing in front of him and calmly explaining how the Order had thought he was the traitor all along and Remus was pretending to take it all very well, Remus was actually coming to the conclusion that he had had sex with Sirius only enough times to count on two hands and a foot.

    Remus Lupin had a very sudden, very quiet, mental breakdown. A psychotic break, he learned that it was called later. He very calmly decided that if he was going to hell in a handbasket, he was taking as many people as possible with him, and then he left London without saying another word to anybody.

    He traveled shiftlessly for a few months, before deciding to cross the big pond and wreak havoc in the United States, where the wizard population was negligible and thus the chance of being caught were greatly reduced. Additionally, the fools there would let you do just about anything if you had an official looking piece of paper that said you could. He charmed himself a passport and a new identity, using Sirius' old nickname for him and the most ridiculous first name he could think of.

    And then he proceeded to have sex with as many people as possible.

    He stayed in New York City for a little while, deciding which career would bring him into contact with the most people with cold calculation, then cheated his way through the training program so brazenly that Sirius and James were probably aflame with pride in their respective cold holes.

    It wasn't hard, Remus discovered, to find men willing to fuck at the drop of a hat, not in New York or Los Angeles, or any of the dozens of places in between. It didn't hurt that Remus had always carried a supernatural kind of grace, one that was very visible on the dance floor of any club you could name, and clearly would translate to the bed (or a bathroom stall) very well.

    He kept track ruthlessly at first of how many people he'd possibly infected, then lost count someplace in the three hundreds. At the end of two years, Remus figured he'd fucked about five, six hundred people, give or take.

    He told them he was French-Canadian; they thought he was exotic. He used all of James' old pick-up lines; they thought he was charismatic. There was nothing he was afraid of doing, no kink too great or small; they thought he was the very embodiment of the era of sexual independence.

    And then, just as suddenly, Remus woke up morning, hungover and tangled up with people he didn't know, and decided he'd simply had enough of it. He packed up his things as easily as he'd done the first time, and returned home to London. On the plane, he wondered whether he'd recovered finally from the first breakdown, or had another. He realized that he didn't care.

    He told no one where he'd been or what he'd done, and after not such a long time the memories of those years faded to a sort of bright blur. A bit longer than that, and it all seemed like a bad movie Remus had watched once, when Remus fleetingly thought about it at all.

    Halfway into the next decade, Remus was having tea in the Hogwarts staff lounge when Professor Flitwick struck up what seemed to be a rather random conversation.

    "Do you know," he asked, waving a wizarding journal about, "about that epidemic Muggles are having over in America?"

    Remus murmured that he might have heard some such thing.

    "The Muggles are saying it's some sort of new virus," Flitwick continued, "but some Squib researcher is claiming it's the same virus that causes Lycanthropy!"

    Is that so, Remus shrugged.

    "Turns out Muggles can't be werewolves," Flitwick had worked himself up into his lecture mode, "because it takes an ungodly load of magic to transform, but they can catch the virus. Eats away at their immune systems until they just keel over from exotic diseases! Must do the same thing in werewolves, only with the accelerated healing, nobody's ever noticed before!"

    Very interesting, Remus agreed.

    "They think they've got a 'Patient Zero' now," Flitwick returned to the journal. "Some airline steward who slept with hundreds of people in cities across the country. Can you imagine! Says his name is," Flitwick consulted the article. "Gaeten Dugas."

    "That," Remus announced calmly, "is the most ridiculous first name I've ever heard."