User blog comment:Hawkinz340/Law is the traitor!/@comment-84.227.112.215-20131009130906

It's certainly no direct betrayal: Law didn't do anything to harm the Straw Hats and actually bought them time to escape. However, as I understand it, he massively deceived them about his goals: His goal never was Kaido and in this sense the alliance is void. He always wanted revenge on Doflamingo for whatever reason we get in the coming flashback. For this end only, he made the alliance, not to weaken Kaido, but to destroy Doflamingo with the Straw-Hats' support. He has no further business with the Straw-Hats than their help in taking down Doflamingo. While this is no direct backstabbing, I agree here with Zoro with respect to Usopp's re-joining: You can't pull off sh*t like that and expect that everyone just shrugs it off.

For example, I think he just made up the 30% figure to be low enough to dare Luffy's taste for risks, but high enough not to scare off Usopp or Nami (it's absurd anyway to give chances of succeeding in such a venture in percentages). Also, to blackmail Doflamingo into leaving the Shichibukai made some sense to me at the time (maybe lure Kaido out, distract Doflamingo from the factory destruction team with the return of Caesar), but now I think it was just another move to take revenge on Doflamingo and had nothing to do with Kaido (and Law deceived the Straw-Hats about this the same way Oda deceived me).

However, I see this working out (after the flashback) with Law going down against Doflamingo, Luffy saving and forgiving him in his usual naive manner and defeating Doflamingo himself (perhaps with help from Law?) and Law afterwards pledging the support of his crew to the Straw-Hats in gratefulness. Also, Law's big goal is to take revenge on Doflamingo, not to become Pirate King, so that's one rival less for Luffy and Law's support for Luffy might take the form of "You helped me achieve my dream, now I'll help you achieve yours".

As for the match-ups, I've no idea except from the inevitable Luffy vs Joker. Sorry for this overly long post...