B.J Penn is a mystery. At times, he looks like the best fighter in MMA's short history, a whirling dervish who combines slick submissions with punching power and great takedown defense. In other moments, times when true champions step up and seize their own destiny, Penn is nowhere to be found. Time and time again he's lost when it counted the most.

Who is the real B.J. Penn? Like death, the former UFC champion has five faces.

The Phenom:

Caol Uno came flying across the cage at UFC 34, a mere blur. It was hard to make him out clearly as he launched an awkward strike, one that couldn't quite decide if it was a flying knee or a kick. It was supposed to be a bravura display of aggression, was supposed to set the tone for the violence that was to follow. B.J. Penn? He wasn't impressed.

The young Hawaiian had made his UFC debut six months earlier against wrestler Joey Gilbert. But he introduced himself to fans that night in Las Vegas with a lightning fast combination of punches. Uno dropped to the mat, his false display already forgotten. Penn, after just 11 seconds, was done for the night.

He sprinted to the back, eschewing the niceties like the official announcements and a post fight interview. Earlier that year Uno had taken UFC lightweight champion Jens Pulver to the limit, losing a majority decision in a razor close fight. Penn hadn't even given him a chance to warm up. This kid was on another level.

See Also: vs. Din Thomas (UFC 32); vs. Takanori Gomi (Rumble on the Rock 4)

The Disappointment:

Pulver wasn't supposed to stand a chance against Penn. The Jiu Jitsu ace was too fast, too strong, had too much power in his hands. What he lacked was Pulver's heart. The Pat Miletich prodigy controlled where the fight took place at UFC 35, executing his sprawl and brawl gameplan to perfection.

Penn certainly had his moments. At the end of the second round, Pulver was literally saved by the bell. Penn secured an armbar with just seconds to go in the five minute period. Replays show Pulver actually tapped out, but did so a moment after the horn sounded, ending the round.

In what would become a pattern throughout his career, Penn wilted as the fight went on. Pulver survived the early storm and by the fifth and final round was pounding away at Penn standing. His hand was raised, tears pouring down his face, Pulver taught Penn what it meant to be a champion.

See Also: vs. Caol Uno (UFC 41); vs. Frankie Edgar (UFC 112)

The Champion:

Penn had failed twice to win lightweight gold. The Pulver fight humbled him. A draw with Uno, a man he had once beaten in less than a minute, crushed him. The division was in chaos and rather than wait for White to decide what to do with the 155 pound class, Penn set his sights on the top welterweights in the world. Originally, Penn wanted to test himself against Sean Sherk. White, a man who doesn't think small, suggested champion Matt Hughes instead. If you're going in, why not go all in? Before their third fight, I broke the UFC 46 bout down at Bloody Elbow:

Despite the size difference, Penn felt a bit like the wrestler's Kryptonite. Even if Hughes did what Hughes did best, slam him to the ground, Penn would present a difficult challenge for the Pat Miletich product when the fight hit the mat. And to prepare for the best wrestler at 170 pounds, Penn took his training camp to Oregon to work with Randy Couture and his team of hard-nosed wrestling greats. In his heartfelt autobiography Why I Fight, Penn talked about the joy he got from frustrating the larger Couture in training. But now, with a title and pride on the line, the training took a turn towards the serious. Penn explained that Hughes was a good wrestler - the guys he was training with were great wrestlers:

There was no better training partners if you had to face a wrestler than the guys at Team Quest. After working with them for a couple of weeks, I was even more confident I would win. The guys there, with their all-American collegiate wrestling backgrounds, Matt Lindland with his Olympic silver medal in Greco-Roman and all the others who were just starting to get involved, it was the best place I could be.

In the main event that night, Vitor Belfort dethroned Randy Couture in less than a minute. His glove caught Couture's eyelid just wrong and the resulting cut forced a stoppage. It took Penn a little longer to take the championship from Hughes, but not much. The challenger was able to secure the top position on the wrestler. For Hughes, like most men who made wrestling their life, was clearly uncomfortable there. The goal his entire athletic career was to stay off his back. Being there, naturally, just felt wrong.

He attempted several sweeps, but Penn was able to maintain control. A big right hand rocked Hughes and Penn was able to advance to a full mount. A desperate Hughes gave his back, but instead of trying to escape or defend his head, he attempted a half hearted footlock. Penn, with nothing in his way, no hands to impede his progress, secures the rear naked choke for the win.

For Penn, it was a career defining win. For Hughes, it was a relief. The pressures of being champion were wearing him down. He told me it felt good to be able to relax, recharge, get married, and then return for another shot at the gold.

See Also: Sean Sherk (UFC 84)

After the break: Two more faces of Penn.

The Buddha:

Penn's title win over Hughes was his last fight under the Zuffa umbrella for more than two years. The promotion was struggling to keep the lights on and was having a hard time offering Penn the fights and money the champion thought he deserved.

Lawsuits followed and Penn ended up in ronin mode, traveling to fight in Japan for the first time and hanging out his own shingle as a promoter with his brother Jay Dee.

These are Penn's lost years. Instead of solidifying his legacy as a great champion, he was fighting unworthy opponents like Duane Ludwig and battling what felt like half the Gracie family in Hawaii. Most notably, "fat B.J." emerged. Without the discipline a promotion like Zuffa imposes, Penn trained, ate a ton, and fought at whatever weight class he felt like competing in.

A string of bad decisions culminated with a bout against rising prospect Lyoto Machida contested at heavyweight. A gargantuan Penn weighed in at a multi-chinned 191 pounds. Something had to give.

See Also: vs. Renzo Gracie (K-1 World Grand Prix 2005)

The Destroyer:

After failing in multiple attempts to reestablish himself at the top of the welterweight division, Penn once again dropped down to 155 pounds. He had long been considered the best fighter in the world at that weight, but had never managed to win UFC gold.

His first fight back at lightweight was a glorified snuff film against Jens Pulver, avenging his loss all the way back at UFC 35. The fight gave Penn closure on that lingering pain and served as a springboard into title contention. Champion Sean Sherk had been stripped of his belt after testing positive for steroids, so Penn and Ultimate Fighter winner Joe Stevenson duked it out for the big gold belt.

Stevenson was no match for Penn, who opened up a disgusting cut on the wrestler's head and then choked him out, both men soaked in Joe Daddy's blood. Sherk proved little more in the way of competition and Penn absolutely brutalized a string of challengers including Kenny Florian and Diego Sanchez.

See Also: Vs. Matt Hughes (UFC 123)

Which Penn will show up to face Jon Fitch at UFC 127 this weekend? That's the beauty of a Penn fight. Life is a mystery and so is a true mat artist like Penn. Penn could demolish Fitch in seconds or lay passively underneath the wrestler for three long rounds. And neither result would shock a single living soul. It's part of what makes Penn one of the most exciting and beguiling fighters in MMA history.