Pitting WWE's heroes against each other is a tricky endeavor with big rewards.
When Daniel Bryan challenges John Cena for the WWE Championship at SummerSlam, there will be no villain to root against. It will be a feud of face against face, fan favorite against fan favorite.
These feuds force the audience to pick sides.
These matches become more of a popularity contest than a morality play. The audience has to choose which superstar to pledge allegiance to.
In traditional good vs. evil stories, there is little choice to be had. When Alberto Del Rio beats his personal ring announcer with a bucket, the majority of the audience instantly sides with the victim and not the merciless attacker.
Fans root for the underdog, the righteous and the wronged.
In a face versus face feud, fans are asked to be more engaged by making them choose between their idols.
WWE cannot depend on the standard narrative here; it is forced to be creative with its storytelling.
Can Bryan vs. Cena be powerful without traditional good guy/bad guy roles? Can it be just as exciting and memorable as matches with a clear hero and a clear villain?
Looking back at some of WWE's past attempts with these types of feuds proves it can.
Ultimate Warrior vs. Hulk Hogan
Even though this is the oldest example here, it is the most like Bryan vs. Cena.
Hulk Hogan was the established megastar. He'd been the unbeatable WWE champ for a long time, fending off giants, monsters and WWE's scum.
Ultimate Warrior represented change.
He was more energized and darker than his opponent. Warrior was a newcomer, a popular upstart looking to dethrone the long-reigning king.
That's essentially the same storyline for Bryan and Cena. Fans who choose to stick with Cena are supporting the status quo, the dependable, consistent star. Fans who support Bryan are in favor of a changing of the guard.
Hogan and Warrior built up their WrestleMania match as the ultimate challenge. Warrior represented the biggest threat to Hogan's title reign, a man as powerful as he was. The storyline also centered around champion facing champion.
It remains one of WWE's most memorable feuds, no villain required.
Undertaker vs. Shawn Michaels
Undertaker had some dark qualities about him, but when he faced Shawn Michaels at WrestleMania XXV, he was still a fan favorite.
Both he and Michaels were among the most popular superstars on the roster. Instead of trying to turn the audience against one of them, WWE chose to have face battle face.
This forced WWE to compose a story that was much more unique and intriguing than the typical "good guy gets revenge on bad guy" tale. It was instead a match to decide the ruler of WrestleMania in a way. Michaels had long been known as Mr. WrestleMania and Undertaker had put together an impressive undefeated streak of 16 wins.
There was a contrast of Undertaker's dark persona with Michaels' religiousness, but the heart of the narrative was competition.
Each man had plenty to prove and plenty to lose which is a recipe for exciting wrestling. Without a championship, Michaels and Undertaker managed to elevate the value of victory. There was also an air of mutual respect, one shared by Cena and Bryan.
Michaels said, "I respect The Undertaker, but I am not afraid of The Undertaker" echoing the sentiment Bryan has expressed toward Cena in recent weeks.
The Rock vs. John Cena
Cena knows firsthand what a successful face vs. face feud looks like.
Say what you will about the failings of either of their WrestleMania matches, but the stories leading up to the clashes with The Rock were top-notch entertainment.
Two of the company's all-time best set out to define their legacies against each other.
Their two matches were about more than wins and losses, about championship belts and momentary glory. Each man's place in history was at stake.
This is the key to an effective feud that has no heel, finding a way to raise the stakes and making winning or losing a monumental achievement.
After losing to The Rock the first time around, the second match centered around Cena's road to redemption. Winning became a way to stop his downward slide and to prove to himself, to The Rock and the WWE fans that he was capable of beating The Great One.
Their star power and their story gave their rematch a big-fight feel that Bryan and Cena should aspire to achieve. The fact that both Cena and The Rock were faces made this match about more than good conquering evil, but one man's will winning out in a tug of war.
WWE would be wise to steal some of the emotion and epic feel of Cena's feud with The Rock when he faces Bryan. Likewise, there is plenty to learn from about heroes battling heroes in the Undertaker vs. Michaels battles as well as Warrior's triumph over Hogan.
A face versus face feud is no cookie-cutter story, but when approached with passion and creativity, it can create magic.