I guess you know that you're in a super-hero universe when you get one of those "Stan Lee Presents"-type mini-origin boxes right above the story title:
(Of course, if the reader can't identify who is narrating, that suggests the writer and/or artist aren't doing their job too well, or that the reader is kinda dumb, so it's kind of an insulting convention. Thanks, DC!)
So, , anyway, that's our nu52 Constantine--after a tragic origin, he goes around trying to prevent others from getting too powerful. So now he's an altruistic sonuvvabitch.
Also, magic is really, really corrupting. Take this (which was in the preview published last month, so it's not much of a spoiler):
Of course, given the ballyhoo about moving John to the nu52, this book really has frak-all to do with the nu52. We know the writing assignments was jiggered around before the first issue even came out (Yay, DC management style!), so it's hard to know who was responsible for what, but Lemire and Fawkes are credited here, and of course they currently write JL Dark. JL Dark, which is chock full of magic users. JL Dark, in which we've never seen mentioned this theorem that magic corrupts everybody, eventually,so we should be concerned every time Zatanna opens her mouth.
Heck, JL Dark is never even mentioned in this issue, nor are any of the other nu52 mystical characters. So maybe not the best start in tying into this universe you were so eager to have Constantine join, is all I'm saying.
Still, as I tweeted earlier in the week, "If you can pretend that he's not the real JC, and ignore the damage to other DC magical characters, it's not entirely awful."