When Brock Lesnar announced that he was quitting WWE following his win over Triple H at SummerSlam, it was obviously a ploy to keep him off television. Lesnar has to return at some point, though, and when he does it will be as a stablemate of WWE Champion CM Punk.
Because of Lesnar's UFC background he can be a big money-maker for Vince McMahon and the WWE, but since his contract limits his appearances, it is very difficult to keep him relevant and important in the eyes of the fans. Having him return as a partner of the WWE Champion would be a great way to ensure that he's prominent as soon as he comes back, though.
Seeing as Punk has aligned himself with Lesnar's associate, Paul Heyman, Punk and Lesnar together would be a very natural fit. Wrestling always seems to be better when a dominant heel stable is in power, but aside from the short period of time in which Nexus was legitimate, the WWE hasn't had that in several years.
Punk and Lesnar together with Heyman as their mouthpiece, as well as perhaps Big Show due to his past partnerships with Heyman, would be fantastic and would surely take the WWE by storm. Lesnar generally isn't one to share the spotlight, but working with Punk and Heyman would mean that his weakness on the mic could be hidden and he could focus on being a destructive force, which is what he does best.
Although it would start off taking a backseat to Punk, it could eventually lead to a falling out of some kind. At some point between now and Royal Rumble, Punk, Heyman, Lesnar and Big Show will all join forces. They'll appear to be a cohesive unit on the surface and will make things a living hell for John Cena and other top faces in the company.
Punk will retain his title until Royal Rumble, often with help from Lesnar, and he will then take on The Rock at the Rumble. That is when the dissension will begin as Lesnar will inadvertently cost Punk the title, ending his year-plus reign as WWE Champion.
John Cena can then win the Royal Rumble and set up a possible Fatal 4-Way at WrestleMania with The Rock vs. Punk vs. Cena vs. Lesnar for the WWE Championship. I'm obviously speculating to a great degree and making some pretty bold predictions, but I feel it would be a logical route to take.
Lesnar is only going to remain a secondary figure for so long, so it can be said that he accidentally cost Punk the title, but it would later be revealed that he did it out of spite and jealously due to the fact that Heyman decided to back Punk and forget about Lesnar.
Punk and Lesnar could both still remain heels, with Cena and Rock playing the face roles. Not only would the match be one of the biggest and most star-studded ones in WrestleMania history, but it would make an incredible amount of sense since every wrestler would have some sort of history with each other.
Even though that would be a lot of top-level talent in one match, the rest of the card could adequately be filled in with potential matches like The Undertaker vs. Chris Jericho and Triple H vs. Shawn Michaels, if the rumors of him returning have any merit. I'm not sure what others think, but I feel like that would be the best main-event card in WWE history.
In order for all of that to happen, though, it's contingent upon Punk and Lesnar teaming up first. It works from a storyline perspective thanks to their respective relationships with Heyman and breaking them up down the line makes just as much sense.
The WWE has an opportunity to do something very special with Punk's dominance and partnership with Heyman, so hopefully that leads to a heel stable and ultimately a marquee match at WrestleMania.