ESPN Mixed Martial Arts

Brothers Ken and Frank Shamrock have sparred, both physically and verbally, for the better part of 15 years.

Older brother Ken, a UFC Hall of Famer, has said that younger brother Frank, a former UFC titleholder, is an ungrateful punk who disrespected their father, Bob.

Not to be outdone, Frank has accused Ken of guarding his turf with excessive zeal. He also accuses Ken of ruthlessly degrading him and labeling him a subpar talent.

In March, the mud slinging reached a different level of enmity, as Frank accused Ken of being a steroid abuser.

It comes as no surprise, then, that the brothers are on the cusp of settling the intra-familial drama that has simmered for so long. They have each signed a contract, in principle, to settle their family feud in a most public fashion: they will face off, in a cage, in a pay-per-view contest.

There are plenty of particulars to iron out, like the date (probably sometime in April), the venue (none has been chosen) and the promotional and broadcast partners to be involved (Elite XC, CBS, and Showtime, with perhaps some other co-promoters), before what is believed to be the first brother vs. brother faceoff in fight history becomes a 100 percent done deal.

"We've both signed a contract to fight each other," younger brother Frank Shamrock told ESPN.com. "Ken is down with it. We talked about it two years ago, and we've agreed materially to fight."

"Will the fight happen? Absolutely," Ken Shamrock told ESPN.com. "He's got a buttkicking coming to him. Everything I've learned, everything I have bottled up in me, is going to come out on him. I've still got love for Frank, but I'm angry at him."

Ken Shamrock, the 44-year-old UFC and WWE veteran, was supposed to take on Kimbo Slice in Florida on Oct. 4. A loser of his last five fight (all by KO or TKO), the Slice tussle was perceived by many as his final shot at a high-profile conquest. Six hours before the main event, however, Ken was rolling with a training partner, and after taking a bump on the head, some scar tissue over his left eye opened up. He needed six stitches to close a gash, and the Florida commission scratched him from the card.

This development put the Shamrock vs. Shamrock scrap on the front burner.

Frank, 35, last fought in March. He lost via TKO to Cung Le, and has fought only sporadically since 2000. If family bragging rights were to be hashed out, the fight had to be booked soon, so Frank is especially keen on making it happen.

"The fight has a cool hook," Frank said. "Brothers beating each other up. Everyone wants to see that."

Elite XC head of operations Jeremy Lappen sees the promotional possibilities in a bro vs. bro throwdown. "They're talking about doing it and we're interested in the fight," he said. "It's a storyline everyone can relate to, Cain versus Abel."

The Shamrocks are adopted brothers; both were taken in by Bob Shamrock, who took on scads of troubled boys on his Susanville, Calif., ranch and mentored the wayward souls.

Ken was born Ken Kilpatrick. When he was 10, he bolted from the harsh discipline meted out by his stepfather and landed in Bob Shamrock's care. Almost immediately, he began to concentrate his energy on sports. He took up wrestling and, later, martial arts. In 1982, Bob adopted Ken and changed his adopted son's name to Shamrock.

Frank followed a similar path. Born Frank Juarez, he too chafed under the harsh rule of a stepfather. At 11, he left home and bounced around in group homes and foster homes. At 13, he landed at the Shamrock ranch, and also took the last name Shamrock in homage to the patriarch.

A rivalry began brewing in the mid-1990s. Ken debuted in Pancrase in 1993 and showed Frank the ropes. Thirteen months later, Frank appeared in Pancrase. By UFC 5 in April 1995, Ken was a top draw in the company. By December 1997, Frank owned the UFC's light heavyweight title. Man-sized egos were now in play, and there was jostling for supremacy. Whose methods were more sound? Whose legacy, at the end of the fighting days, would loom larger?

In 1997, a marked deterioration in the brother's relationship occurred. The brothers had a falling out, and since then, Ken has sided with Bob, and Frank has been on the outside looking in.

Muddying the situation is Bob's health. He had a heart attack in September and has lived with type-2 diabetes. His condition worsened after the heart attack and several organs shut down, After several surgeries, he is awake.

Frank believes the presence of his father at the bout would be a vital component of the event.

"He's a big part of this story," Frank said. "He needs to be there. I'd be devastated if he weren't."

Frank and Bob hadn't talked in eight years before Frank visited him in the hospital in Reno, Nev.

Is there not a chance he'd be sad to see his sons battle it out?

"I think he'd be very happy," said Frank. "Listen, Ken and Bob both have amazing hearts. He [Bob] took me off the streets and did the same for so many other kids. This story includes him."

Ken feels his dad will attend if healthy enough. Who would Bob pull for?

"I think he'd root for both of us," Ken said. "But I think he's disappointed in the way Frank has acted to him. My dad loves us both, but I think he'd like to see Frank taught a lesson."

Apart from the obvious desire to pull off a commercially successful event, Frank believes that it is important to share the legacy of the Shamrock name in MMA. He thinks that too many fans believe that the Zuffa-backed UFC is the A-Z of MMA, and wants to set that record straight.

Ken wants to set Frank straight.

"I'm a fighter, he's a fighter," Ken said. "He feels he's better than me, but I always spanked him in the gym. Now he wants to show me. I figured he'd wait until I was 50 years old, but I guess he's waiting until I turn 45."

For the record, Cain defeated Abel via first round KO in their scrap. Brothers have been going at it for many a moon. If only pay-per-view was around in their day …

Michael Woods, the managing editor of TheSweetScience.com, has written for ESPN The Magazine, GQ and The New York Observer.