And why is KJ Apa from Riverdale denying he's him? A timeline of the hip-thrusting, synth-pop-crooning online sensation Like Austin Powers with abs, Mr. Fantasy emerged from the depths of TikTok last summer, all mop-top bob, funky teeth, and unnerving hip swivels. A pop singer with a British accent and an eye toward Hollywood, he romped through our social feeds — often shirtless, always undulating — and hip-thrusted his way into our reluctant hearts. From day one, though, fans noticed an uncanny resemblance to the star of a similarly campy, horny TV show: New Zealand-born actor KJ Apa , who dutifully, painfully dyed his hair red for seven years to play Archie in Riverdale , a fever dream that made millennials feel funny about the comics they used to read in the grocery-store checkout line as kids. Now, though, Apa has declared war on the foppish “fraud” at the very moment that Mr. Fantasy’s debut album, Fantasyland , shimmers on the horizon. From Mr.…