Each of the Ta'veren have a counterpoint, a Ta'maral'indemela if you will. Meaning literally, "pattern destined enemy." A term I mostly made up for this concept.
Consider Rand, the Dragon Reborn. His counterpart is fairly obvious: Ishamael/Moridin. An equally devastating and powerful male channeler, one of the Forsaken, also wielding thousands of years of memories, who rises to the rank of Nae'blis, favored champion of the Dark One. He is tied intrinsically to Rand's fate.
Consider Perrin, the Wolf King. His counterpart is also fairly obvious: Slayer. Of two souls like Perrin, but both human, both princes who would never be king, where Perrin is the King that should have been a peasant. Like Rand and Ishamael, Perrin and Slayer share a domain: Tel'aran'rhiod. While Rand and Ishamael both take advantage of TAR, it isn't "theirs" the way Perrin and Slayer own it.
And then consider Mat, the Gambler. Who is his? Well, this is all conjecture, so maybe there isn't one. But it's fun to think about. Who stands as a corrupt mirror to Mat? Fain, imo. If Mat is the living embodiment of Fortune, then Fain is the living embodiment of Misfortune. The man himself is a case study in being in the wrong place at the wrong time. And because of it he gains power, through Mordeth, Mashadar, and Machin Shin. He is controlled and dominated by the memories that possess him - inverse to Mat, who is overwhelmed by the memories of Manetheren, but maintains his identity through it and gains power from them rather than giving himself to their power. They are antipodes.
You can even find some symmetry in Mat being "the Fox that makes the Ravens fly" and Thom's first comment about Fain being, "there's more Raven than Man in that one." Though it's arguable if that was intentional or just conveniently works out. Their souls were joined by the ruby-hilted dagger, too.
And Fain never stood a chance pitting Misfortune against Fortune. It was anticlimactic for sure, and perhaps there was way more than could have been done with it, but it still works - imo - because he failed his way right to death at Mat's hands, As has been noted elsewhere, the Pattern was done with him and just sent him to be dispatched. He still wreaked havoc on the battlefield to both sides, he just didn't get a big epic chapters long fight scene like Slayer and Moridin did. And if we look at it from this perspective, though perhaps not satisfying, one can see how it's at least fitting.