I wrote some Leverage xovers, but I don't think they meet the requirement of fixing what you didn't like about the show:) Both are crossed over with SPN, so you might find them interesting anyway? http://archiveofourown.org/users/epeeblade/works?fandom_id=5280

The other one I wrote (The New York ComicCon Con) involves just Elliot, Parker and Hardison, no Nate or Sophie in sight:)