Harris grew up in the same poverty-stricken Miami suburb as Slice. They went to high school together and maintained a relationship afterward. They are both big, bearded, tattooed men -- with a long history related to backyard brawls.
Of course, the major difference is just about everyone knows Slice, whose birth name is Kevin Ferguson. Slice's Internet fight videos have generated millions of views and he has drawn massive television ratings as a mixed martial artist in several promotions.
Harris has never reached a similar status. He was virtually unknown before the release of "Dawg Fight" last year, a look-back documentary that focused on his role as a promoter of backyard fights years ago.
According to Harris, he could have achieved the same notoriety as Slice but efforts were made to prevent it. Harris says he participated in two brawls similar to those that made Slice famous, but footage of the better one disappeared. The reason, in Harris' opinion, was that his emergence would have been bad for Slice.
"What was good for the gander wasn't good for the goose," Harris told ESPN.com. "Kimbo was turning pro in 2007, so I said, 'Let me be the new face of the backyard.' There were people telling [Slice's manager, Mike Imber] to invest in me, but they were focused on Kimbo.
"I fought for them a few times underground. Why has my footage never been seen? I've never seen my own footage. They've got it locked away."
Both Slice and Imber have refuted Harris' claims. According to their side, Harris was scheduled to fight multiple times with a camera crew present but backed out of each one. Harris counter claims that yes, he did refuse to fight on one occasion, but only because the fight was put together last minute and he had suspicions Imber brought him in to lose.
"He had people around him saying, 'Yo, Kimbo, you better watch that dude. He'll take your spot,'" Harris said. "I started seeing a change, to the point they were trying to get me physically hurt. Like, ask me to go somewhere and then already have a fight set up. That didn't happen with Kimbo. Whenever he got into a vehicle, he knew exactly what he was getting himself into."
Regardless of where the truth lies, there are unmistakable signs of bad blood between the two -- which is why they were booked to fight in the co-main event of Bellator MMA"s latest "tent-pole" event, Bellator 149, at Toyota Center on Friday night (Spike TV/ESPN Deportes, 9 p.m. ET).
Slice (5-2) is coming off a comeback knockout win against now 52-year-old Ken Shamrock in June. The fight was sloppy and even drew some wild accusations it was fixed, but it was a tremendous success -- setting a new promotional viewership record with 1.58 million average viewers. Shamrock (28-16-2) will also appear on Friday's card, in a headlining spot against fellow icon Royce Gracie (14-2-3), in their third meeting overall and first since 1995.
To just about any observer, it's a bit of a circus. Shamrock and Gracie are a combined 101 years old. Harris hasn't fought since 2011. Prior to Bellator's offer of Slice, Harris wasn't even training MMA anymore -- and doesn't have high aspirations of fighting beyond Friday.
"I've been focusing on my community, building other guys who thought they could be the next Kimbo," said Harris, who still resides in the same Miami suburb. "I probably would have been done if it wasn't for this call. The only reason I'm out here is because it's Kimbo. If it was against anybody else, I wouldn't have taken it."
During an open workout earlier this week, Harris turned heads with his lack of technique while hitting pads. Slice brought the subject up on Wednesday during a news conference, accusing the 38-year-old of "looking like s---." Harris told reporters he looked bad intentionally.
That said, Harris, who is a 3.5-to-1 betting underdog, said he understands odds are against him -- but the opportunity to set the record straight, according to his version of the facts, should be enough to will him to victory on Friday.
"I know what I'm up against," Harris said. "It only takes one punch. I'm a brawler. I'm not an MMA fighter. You know as well as I know my friend, this s--- is not getting out of the first round.
"I turned to this dude at the last event and told him, 'Don't forget, bro. I'm still living where you came from. You done made it. I'm still in the hood. I'm doing better, you know what I'm saying, and it's about to get better but my mentality is still of a savage. To beat me you've got to kill me, and I don't think he wants it that bad. I'm doing this because it needs to be done."