At WrestleMania 29,  The Undertaker looks to extend his unprecedented undefeated streak to 21-0 by silencing the longest-reigning WWE Champion of the modern era — CM Punk. There is certainly no love lost between the two WWE Superstars — even before Punk took possession of Paul Bearer’s urn and used it as a means to get under The Deadman’s skin, the Superstars had crossed paths before. But now, The Second City Saint is a different competitor — a better competitor — and The Phenom’s Streak is in real jeopardy.

There is more to the coming battle, though, than just the personal enmity and history between The Undertaker and CM Punk — in fact, the greatest variable of the entire equation may be Paul Heyman.

Heyman and The Phenom share a harsh animosity of their own — a rivalry that endured for years and became bitterly personal with the inclusion of Bearer.

It’s possible that in another lifetime, Heyman and The Phenom could have been allies, but the events transpiring in the early years of 21st century tell a different story. After nearly a decade, could Heyman be the deciding factor in the battle at WrestleMania 29? Why would he alter the course of history other than to feed his own insatiable ego? The answer is simple — payback.

Heyman enacts Mr. McMahon’s orders against The Phenom

One of the earliest encounters between Paul Heyman and The Deadman occurred during Heyman’s tenure as SmackDown General Manager in 2003. On the Oct. 23 episode of SmackDown, The Phenom battled WWE Champion Brock Lesnar and U.S. Champion Big Show in a Handicap Match. At the time, The Undertaker was embroiled in a bitter rivalry with Mr. McMahon — thus, as SmackDown General Manager, Heyman tried to make the evening a living hell for The Phenom.

Although The Deadman was victorious, Heyman changed the contest to a Best Two-out–of-Three Falls Match after The Phenom pinned Big Show. When The Undertaker tried to win the second fall by count-out, Heyman changed the stipulations to include no count-outs. When Lesnar and The World’s Largest Athlete were disqualified, The SmackDown GM again changed the bout to a No Disqualification Match. Although The Undertaker was ultimately victorious, the match initiated the animosity that would exist between The Phenom and Paul Heyman.

The Undertaker Tombstones Heyman

Following The Undertaker’s return at WrestleMania XX, he crossed paths with Heyman once more, appearing after then–WWE Champion  Eddie Guerrero defeated  Rey Mysterio following a Gauntlet Match. Heyman had entered the ring to confront Guerrero and Mysterio about his desire to rid SmackDown of them in the upcoming draft. As Heyman tried to exit, Paul Bearer and The Deadman made their way to the squared circle.

Frozen in fear, the loud-mouth former SmackDown General Manager was pushed toward The Undertaker by Guerrero and Mysterio. Without hesitation, The Phenom hoisted Heyman up and delivered a Tombstone Piledriver. Whether it was payback for Heyman carrying out Mr. McMahon’s orders month earlier or The Deadman reasserting his dominance is inconsequential, the WWE Universe went crazy at the sight of Heyman getting his due.

The Dudley Boyz kidnap Paul Bearer

Three months after The Deadman unceremoniously Tombstoned Heyman, the former owner of ECW was no longer SmackDown General Manager and was instead back to his role of managing individual Superstars and tag teams. Reappearing on the May 27, 2004, episode of SmackDown, Heyman aligned himself with  The Dudley Boyz and ordered them to find a way to dominant the blue brand.

The Dudleys responded by kidnapping Paul Bearer, leaving the urn unguarded for Heyman to collect.

Heyman taunts The Undertaker

One week after The Dudleys kidnapped Paul Bearer, The Undertaker battled Booker T in SmackDown’s main event. The match ended in a No Contest when Heyman interrupted the bout and delivered an ultimatum to The Deadman. Either The Phenom join forces with Heyman and The Dudleys or Paul Bearer would endure further hardship and injury at the hands of those damned Dudleys.

The Undertaker joins Heyman

After a week to debate Paul Heyman’s ultimatum, The Undertaker decided to swallow his pride and take the honorable path and protect the well-being of Paul Bearer. As a result, The Phenom joined forces with Paul Heyman — who used the urn to take control of The Deadman.

What occurred that evening on SmackDown is surely engrained in the mind of The Undertaker as he prepares to battle CM Punk. That night in 2004 inside Long Island’s Nassau Coliseum, The Deadman kneeled before the urn-wielding Paul Heyman — an instance that stands as one of the most surreal moments in the storied career of The Phenom.

Paul Heyman begs forgiveness from The Undertaker

At The Great American Bash 2004, The Undertaker battled The Dudley Boyz in a Handicap Match with Paul Bearer locked inside a glass crypt. If The Deadman lost the battle, Bearer would be cemented inside the enclosure.

The Phenom defeated The Dudleys, but he shocked the WWE Universe when he willfully buried his former manager in the cement anyway. One week later on SmackDown, Paul Heyman begged The Undertaker for forgiveness. It seemed as though Heyman realized he could not control or defeat The Deadman.

The Undertaker seals Heyman inside a casket

Although Paul Heyman begged for forgiveness, it wasn’t long until he was once again drawing the ire of The Deadman. Encouraging new Superstar Heidenreich to target The Undertaker, Heyman tried to make The Phenom’s life a living hell. Leading up to The Deadman’s Casket Match with Heidenreich at Royal Rumble 2005, The Phenom capitalized on an opportunity to remove Heyman from the equation.

On Jan. 6, 2005, The Undertaker battled Heidenreich and Heyman in a Handicap Casket Match. The bout resulted in Heyman being sealed inside the casket, effectively — and symbolically — ending the animosity between him and The Deadman. Or so it seemed …