In my mind, Chris is definitely Dean. He's the older one, a tough fighter (due to his difficult childhood) with a huge sense of loyalty to his family. Justin is Sam, Chris' younger (but taller) brother who rebels and leaves the family ("goes solo" as it were) because he wants a "normal" life. But he loves his brother and so when Chris comes to get Justin, because he needs help finding their dad, Justin of course drops everything and goes. Oh also, Justin has a girlfriend. I'm really torn between Britney and JC as Jess. Because omg how perfect is Britney as Jess? The blond, love of Justin's life, who tragically burns up on the ceiling (aka marries white trash and has his children). But I could also see JC as Jess, and that way there's some slash going on. And you know JC would dress up as a nurse for hallowe'en.
Anyway, after Britney dies, Justin is determined to find what killed his girl and his mother, so he and Chris set out to find their dad, kill some creepy bad things, and squabble. If you're into wincest, that makes it timbertrick. Oh, as for their father, if you dislike John as much as I do, then you can make him Lou Perlman, who pushes them and takes away their childhood and screws them up emotionally. Or, if you like John, I guess he could be Kevin or something. I don't know.
So they meet various people along the way, like Missouri, who in my mind is Joey. He's friendly and kind of motherly and teases Chris and...can read minds? I don't know. And Meg, the evil blond demon who seduces Justin, is Lance. Haha! Anyway, Justin starts having these dreams and visions, because he's "the chosen one" and Chris is worried and just wants to protect him. And Chris is always having to save Justin from near death. And Justin sometimes fights Chris, but when it comes down to it, he listens to Chris, because there are more important things than killing the demon that killed Britney. More important things, like Chris. And then they get hit by a mack truck.
Oh, and there's a really funny episode where Chris is afraid to fly. And another one where they play practical jokes on each other, because you know Chris and Justin would be all over that. You know what? Joey could also be the girl who works at the auction house, who Justin kisses, because obviously Joey would totally be worth kissing, even if he were still mourning Britney. And Joey would totally be into the hunting stuff.
Okay, that's all I've got for now. :)