Well, I read further...and it's just not making me all that angry, to be honest. The first chapter did--it seemed like pure theft of Jack's storyline--but afterwards...I mean, it's not all that good (apart from the SPaG, which is either perfectly fine or just lacking anything too glaring), but--I don't particularly want to set fire to it? I mean, it's filled with annoyances--Isolda Frost, for instance, certainly looks a lot like Jack Frost, and shares part of his name with no explanation to boot, and the unmarked POV shift I just saw was pretty jarring--but...it's not particularly filling me with rage. Not like some others I've seen. If you want to take it down so badly (and I assume you're made angrier by it than I am), I'm happy to potentially co-write with you; alternatively, you can find someone else--there are definitely other Rise of the Guardians fans around here--or just wait until you have permission. Your call.
And yeah, co-writing with one permission-less partner is a thing. See this section of the Permission FAQ article on the wiki for details.
~DF
PS: As an analysis--I've finished reading it, and, well, the good thing is that you've got some interesting concepts in there, and some cool story ideas (as well as generally good spelling and grammar, as I mentioned earlier). The main issues are the constant POV shifts, the cliches and imitations/ripoffs in some of the characters and backstories, and the fact that it's supposedly a movieverse fic but seems to be using what I assume are the book names. As well, it's missing a disclaimer, which FFN fics are supposed to have. Those are the main things I'm seeing; the rest are more minor nitpicks. In short, it's not the worst of the worst--but it's pretty far from the best of the best. I think I probably wouldn't take it on on my own, as I don't think there's much to make my agents angry or to use to make a good story for them, but if you've come up with agents who would be angry at it (or something along those lines), then I'm fairly sure an agent or two of mine would be able to grow a bit by being a sort of amused tag-along. At the very least, I'd be able to write them as semi-relaxed/slowly gaining tension for a change. But yeah--your call. And keep in mind that other people have seen Rise of the Guardians, and may see more mission potential for their agents in this than I do.