It's half-fake, I guess you could say.
Leon made it up, but some parts are borrowed from reality.
Mysty is real. The 'we're best friends' part is real. My fanaticism of NASCAR is real. (When Tony Stewart nearly wrecked in the Sprint Unlimited a few days back, and saved it, and Jimmie Johnson, Kurt Busch, and Jeff Gordon ended up wrecked instead... well, I'm glad nobody else was in the room, because that would have been embarrassing how much I jumped up and danced around the room.)
The 'Astral Plane' is not real. 'Tommy' is not real. [Leon, you really should've called him Frank. You can guess why
] I'm scared to death of power tools and fire -- I'd never touch a blowtorch in reality. And finally, in the story, there is a 'demon' of sorts (the Evil One is such a lame name, huh), but Mysty doesn't die... Well. Not yet, at least. (evil grin)