The mission for Are You the One? love hopefuls is to find The One -- but between the stress of Truth Booths, Blackouts and unrequited love, participants have been known to well, bicker endlessly. Enter the alums from the dating series who will be featured on the upcoming Challenge: Rivals III juicy installment...

Briana and Brandon were actually deemed by a group of experts to be scientifically compatible on paper during Season 2 -- but when they got to interacting in paradise, they did not get along.

"He thinks he knows everything -- he thinks he's God," Briana admits in the introduction video above. "Everything on this planet Brandon made, so that's why I hate him." This gal is not one to hide how she really feels...

On the opposite end of the spectrum, B-squared's fellow cast members Christina and Nate did enjoy a fun flirtation -- but when they learned they were not a perfect match, their relationship deteriorated.

"There was one particular blowup that I think really sealed the deal for me and Nate beings rivals, because I sat on his bed and he threw a fit over it," Christina discloses in the clip above. Unsurprisingly, though, Nate had a different view of the situation and they definitely "got into it." Note to C: Don't go near N's sleeping space...

Lastly, Cheyenne and Devin had zilch sexual tension (well, according to Chey at least) during Season 3 -- and she took major issue with the way he treated the ladies in the house.

"I would explain to him to not be so disrespectful to women," Cheyenne explains in the video above. "He thinks he's like a mastermind." Meanwhile, Devin chimes in and exclaims he's "really smart." Can't even utter a complete sentence without one of them having a differing opinion of what the other person is saying...

Can these Are You the One? vets play nice and take the Rivals III crown? Watch all of the videos to get a first taste of what lies ahead — and be sure to catch the premiere of The Challenge: Rivals III on Wednesday, May 4 at 10/9c!