Large groups of people were dying. No one really knew why--not for a while, at least. And no one really knew how it was spreading, which was a fact that scared a lot of people. There seemed to be a focus on gay men, which...didn't help to calm the superstitious.
But there were places the infection seemed to skip. Or it would flare and then suddenly stop spreading. Sometimes people got it, had all the same symptoms, then got better with no real explanation.
(Rulekeepers in a hundred different districts had the same conversation: "You know you're not supposed to--"
"And I suppose if you'd been in my place, you'd just have let them die?")
It was an opportunistic infection, and blood-borne, which made it easy enough to hide. You just had to not maul anyone, and not bleed on anyone with an autoimmune disease. As long as you didn't have some random autoimmune disease suddenly infecting a lot of people all at once, a little care and a little inertia kept the werewolves' masquerade together.
It broke rather swiftly after the AIDS epidemic hit.
Once people knew about werewolves, people gradually gave up on arguments like, "But that violates the laws of physics!" Really, after the initial shock, most decent scientists started saying, "So what are the rules of magic?"
There were general murmurs in the vampire community that the werewolves weren't really facing as many difficulties as they might--they'd been good at the publicity fairly early on, focusing on little kids who'd gotten AIDS off of blood transfusions, who'd been saved by werewolf immune systems. It threw gay werewolves under the bus, but the general consensus among the werewolves' P.R was., "...So?"
The vampires decided they could probably swing something similar, and that it would be easier to do so if they chose when they were found, rather than waiting for one of those, "But what if vampires and fairies and and and!" people actually found something. They decided to wait for the werewolf fuss to die down and then come forward.
They placed the emphasis on ingenues with deadly diseases, too, though they pulled the focus to people who had been turned a bit older--200-year-old vampires who looked six tended to be more frightening than someone who had been turned in their 20s.
It worked out pretty well. The garlic-flavored blood packs don't quite taste like real garlic yet, but you can get some really fancy stuff that does, and people have even stopped putting real garlic in now.
It didn't take as long for the fuss to die down the second time--or rather, everyone was waiting for something else to turn out to be real. Mages went next, with the fairies, because they were just similar enough that it made sense for them to come as a package.
The focus of their spin was mainly on the fact that magic only worked on one's own self. "Like, I can change my own hair color"--a pause as the hair goes through a brief kaleidoscope--"but if I tried to do the same thing to you, nothing would happen." The mage shrugged, and after enough people said the same thing convincingly enough, most people stopped fretting so much about mages. I mean, there are places you still don't want to go, if people know you're a mage, or a werewolf, or a vampire, or a fairy, but there are places where you can live mostly unhindered, at least.
No one brought up that "one's own self" was a rather subjective term. There's a reason why so many people are so protective of their tarot decks, for example. And once you realize that, sometimes you can bend your mind to the point where other people do register as part of you--or the land does. The latter is actually pretty common among fair folk. I am my tree; I am my land; of course I am; are you not?
And so everyone pretended that they had dropped their masquerades. To be reasonable, if you're a cute girl who became a werewolf against your will, or a vampire who only became one because you were dying of cancer at 20-40ish, or a mild mage who's willing to look 'normal' or 'cute', or a fairy who can pass for mage, you don't have to hide your magic anymore. If not, you can pretend to be one, or you can keep pretending to be mundane human.
Honestly, I'm still expecting some more mythical creatures to be real. Given how easy all these spins were, I'm guessing someone is still waiting for their moment. Either way, hey, maybe by the time I'm dead you'll be able to actually want to be a werewolf without losing your job.