His name, legally changed, is War Machine.
He has spent time in jail, dabbled as a porn actor and sabotaged his own mixed martial arts career with ill-advised ramblings about President Obama and the late UFC fighter Evan Tanner.
But these days, the 30-year-old welterweight who began life as Jon Koppenhaver is looking to stick to the straight and narrow. Newly signed with Bellator Fighting Championship, which cut him once before, War Machine is on the comeback trail.
"I feel great. It feels good to be out (of jail), it feels good to be back in training," he told The Canadian Press. "I feel like I've kind of got a clean slate. . . . It feels good to have a second chance."
Credit Bellator chairman and CEO Bjorn Rebney for that.
"He did his stint as a guest of the state and when he got done with that, I talked to him a series of times and it just seemed it was no longer about excuses, it was no longer about pointing fingers," Rebney said of his second go-round with the California fighter. "It was more about kind of a very clear recognition that he had made some mistakes — and a recognition that there were some things in his life that he just absolutely had to steer clear of if he were to have a chance to kind of right the ship.
"It wasn't excuse-based, it was more reality-based. It was kind of like he had hit rock-bottom and he recognized it."
Rebney hopes to use War Machine (12-4) in the next welterweight tournament, set for early March.
"The reality is sometimes we lose track of the fact that he's a very talented fighter."
But also a troubled one, with a tough childhood and alcohol-related problems as an adult. Like the grenade tattooed on his neck, War Machine could be explosive inside and outside the cage.
His Twitter bio reads: "I'm a warrior. Made a lot of mistakes but that's life. I learned from them and now I'm gonna climb to the top!"
One of those mistakes was the bar fight at Thrusters Lounge in Pacific Beach, Calif., that led to a year in jail for two felony assault charges. Already on probation for a misdemeanour assault in 2007, he pled guilty as part of a plea agreement.
War Machine was "beyond aggressive, crazy," according to one witness at the trial. The brawl itself was captured by surveillance camera and is available on YouTube.
The fighter says he was celebrating the birthday of a friend, a Navy SEAL who had just got back from Afghanistan. According to War Machine, his friend got into a fight and when the odds got worse, he jumped into the fray.
"It was a big melee and then when all the dust settled, they decided to arrest me."
He was released from a San Diego county jail in July 2011.
"I mean basically it was a big waste of time," he said when asked to sum up his incarceration. "You sit there and you rot. There's nothing good about it and it's nothing I'd ever want to go back and do again."
He spent the first six months in the general population and the last six in solitary, only allowed out of his cell one hour every other day.
He said he couldn't handle his cellmates when he was moved to a new jail with three-man cells.
"It was driving me crazy," he said. "I wanted my privacy. I actually wanted to be in solitary because there's less stress. There's no chance for any fights or nothing. You're just locked in there.
"Basically I told the guards 'Hey man, if you guys get me more cellmates, I'm going to start beating them up.' I was bluffing, I wasn't going to do that but I was trying to make them think I was dangerous. It worked, they knew I was a fighter so they put me in the hole."
It wasn't easy on his wife Zsanett, who is from Hungary and was still adjusting to a new country. They met while she was on holiday in Los Angeles.
Before he went to jail, he took a fight on five days notice against Canadian John Alessio.
"I knew I was going to lose, I wasn't in shape at all but I had to make money to leave for her," he said.
He lost by third-round submission and then served his time.
War Machine says he doesn't believe people change as much as the decisions they may make can change. Translated, he realizes there are some places where trouble is likely to follow him.
"If I warped myself back in time back to that bar and my friend was getting jumped by those guys, I would still punch them," he explained. "I'm still the same guy. I just realize now that I can't be going to those places. So I'm not going to put myself in any situation where I could make a bad choice."
In jail he said he saw too many examples of history repeating itself. Bad places, bad friends, bad choices.
"They have to get rid of those surroundings. My surroundings for trouble is bars. So I have to refrain from going to bars and I'll stay out of trouble. I'm definitely just living more low-key and just focusing on my training and stuff. And not going out any more."
War Machine last fought Nov. 26, stopping former UFC veteran and Sports Illustrated cover boy Roger Huerta in the third round in the main event of a card in Texas.
Both men had seen better days as a fighter and needed a win.
"After a long layoff, being locked in a box, it was a big step-up," said War Machine, who damaged Huerta's ribs en route to the win.
War Machine says he has a good support group in his wife, friends, trainers and students at the San Diego gym called Undisputed where he trains and coaches.
He teaches jiu-jitsu in the morning and kids' MMA classes in the afternoon.
With more than 10,000 followers on Twitter and a history of missteps on his MySpace page, War Machine knows he has to watch what he says these days — "because I definitely think outside of the box on a lot of my views on things."
He says he had a long talk with Rebney about it.
He was told it was basically OK to be wild, crazy and funny. Just stay away from "the really far-off stuff that can offend large groups of people."
"I put a filter on what I say," he added.
He learned the hard way that alcohol and Twitter can be a dangerous mixture. Under his probation, he is not allowed to drink.
"New Years is boring sober ... blahhhh?" he tweeted over the holidays.
Recent tweets have been about who has the best fast food fries and a beef jerky recommendation.
War Machine was introduced to a lot of MMA fans in 2007 via Season 6 of "The Ultimate Fighter."
Being locked in a house for six weeks with no contact with the outdoor world other than to fight and train was especially difficulty given he had been diagnosed with an anxiety and panic disorder.
"I was very uncomfortable in the show. It was actually pretty rough for me mentally."
On the plus side, his December 2007 fight with fellow cast member Jared Rollins in the live season finale was a barnburner. War Machine won by third-round TKO in a bloody back-and-forth bout that fans voted No. 81 in the UFC's 100 top fights.
He was cut after a loss to Yoshiyuki Yashida at UFC 84 in May 2008. He had refused a fight and became a liability after some ill-advised comments about Tanner's death.
A year later, Bellator signed and released him for comments about Obama.
He got into MMA after watching old UFC fights as a kid with his father. They bought some jiu-jitsu tapes to learn more and War Machine joined a gym when he was 14.
His home situation was going south. His father died of a heart attack when he was 13 and his mother had drug issues.
He went to The Citadel, a military college in South Carolina, and loved it. A biology major, he said he was forced to leave early in his sophomore year because his mother spent his college money on drugs.
When he was 20, he came to San Diego to train with Ken Sharmock at the famed Lion's Den. Shamrock opened a lot of doors to the young fighter and introduced him to fellow fighter Phil (The New York Bad Ass) Baroni, who gave him the War Machine nickname.
Koppenhaver legally changed his name after TNA wrestling threatened to sue him because they had the rights to War Machine for their wrestler (War Machine) Rhino.
"No one thought I would really do it. But I did it and that fixed the problem," he said.
Some of his friends call him Jon, others use War. "They go back and forth," he explained. "It's all the same."
But if he meets someone, he introduces himself as Jon.
"The only time it's weird is when I go to the doctor's office or something like that where I have to use my legal name."
His days as a porn actor — "a crazy idea" — are behind him.
"It was pretty awesome," he said.
"I don't know man, you only live once and I think most guys fantasize about trying that kind of thing out. I said 'Screw it, man I have no reason not to.' I was single, I had already lost my UFC contract."
He said he did about 20 scenes over four to five months.
His interests are more mainstream these days. Movies, dinner and the occasional visit to Sea World — he gets in free because the son of a friend works there.
"Just mellow stuff."