The roses, the kisses, extra time in the hot tub. Dissecting the subtle signs on ABC's "The bachelor" can be maddening. Love or the devil is all in the details. But for some at home there's more at... See More
The roses, the kisses, extra time in the hot tub. Dissecting the subtle signs on ABC's "The bachelor" can be maddening. Love or the devil is all in the details. But for some at home there's more at stake. You're about to meet fans taking it to the next level. Placing bets on contestants, making brackets with their favorites, and bringing the competition into their living rooms. Her boyfriend peter greechner are hosting. Gather around the television. So this is pregame. This is all pregame. Reporter: Don't let these smiles fool you. Tonight is about some serious competition. Do you want a beer? Yeah. We don't drink pink wine. Reporter: Wings and pizza. Check. A front row seat. Check. But these frenemies aren't about to watch a football game. And it's too early for March madness. Instead they're betting on another venerable American institution. "The bachelor." Will you accept this rose? Reporter: The veteran show where love is the ultimate competition. And each week women are eliminated until only one remains. Will you accept this rose? Reporter: Megan, peter, and friends Lindsy, Diana, and Jeremy each filled out a bracket after that first episode of the season choosing the women they think will make it the farthest in their quest to win the heart of this year's lucky and controversial bachelor, Juan Pablo. My top three is Renee, Clare, and Lauren S. Reporter: Some of them spent hours analyzing the profiles of all 27 girls. So what are the main things you that look at when you're going to fill out your bracket? Age usually seems to make a difference. In what way? I feel like the bachelors usually tend younger. For me it's like, will their lifestyle mesh up with his lifestyle and where I think he's going. Reporter: But trying to figure out what this former pro soccer player wants hasn't been the easiest. We know the 32-year-old looking for a great stepmom to his daughter Camila and perhaps someone who can help him translate from time to time. If there's any kind of conflict or bump in the road, I would like both. What does that mean? Reporter: The hunk getting hfl into some hot water after apparently telling a reporter why he thinks a gay bachelor just wouldn't work. A charge he tried to explain on "Gma." It was a misuse of a word. It's been hard because to me when I speak English it happened two months of filming, sometimes the words I used were not interpreted the way they should be. Reporter: But our bachelor betors are so worried about spoilers they missed the headlines altogether. First up is Clare. Reporter: We brought along a prop. Should we do this? Yeah. Nikki. Yeah. Nikki is ruining my bracket. Reporter: Could these kind of offscreen viewer competitions breathe new life into America's long-standing affair with the show? I love it. Reporter: "The bachelor" now in its 18th season with a weekly audience of over 9 million. Time for another rose ceremony. Reporter: Even host Chris Harrison admits it's getting more challenging. It's tough to keep it fresh. I mean, how many different dates over 12 years can you create? I mean, how many hot air balloons and diving off cliffs and bridges? There are only so many things you can do. I love the fact that we're starting to really embrace the fact that you talk about spoilers. Things are going to get out. We would really like to keep the ending a secret, but early on, that's fine, embrace the fact that they're dating in public and going out. So we are trying to be as creative as we can but we also don't want to change our show. Reporter: But the show is changing. I'm going to go. Reporter: Unlike seasons past, this year two of the women left voluntarily. With the third-place contestant calling Juan Pablo out in front of millions. I just never honestly feel like you were trying to get to know me. Do you have any idea like what religion I practice, what my political views are, what my -- hang on. What my views on social issues. Things that matter. Do you have any idea how I want to raise my kids? Do you have any idea about any of that? I have no idea about any of that. I think there has become a little bit of gamesmanship on the part of the producers where -- because they do know that the spoilers are are out there, they maybe play with the audience a little bit and try to throw you off the trail. So somebody who ordinarily would have been a front-runner will be buried and sort of pop toward the end of the season to try to keep the audience guessing a little bit. Reporter: This Brooklyn ritual began three season as go, when Megan invited boyfriend peter, a software engineer, to join a bracket with her and her friends. I googled for bachelor bracket online and I didn't really find anything. So just for the five of us I decided to make a website for it. Reporter: His website, thebachelorbracket.com, started with five, growing to 1,300 users last season. And now -- We've had 18,000 new people and growing. Reporter: We showed Harrison the site. The bachelorbracket.com. Unbelievable. Reporter: Players around the world can choose to play the standard game, making their picks after the first episode, or week to week. There are even custom games allowing to you bet on everything from one on ones to makeout sessions. I keep waiting for it to go to Vegas so I can just go and bet the house. But somehow in editing they might switch it and I would probably lose. But no, I try to stay out of that, only because I'm there at the actual time it's all taking place. Reporter: Sorry, Chris, this gang is playing for bragging rights instead. Would you accept this rose? Reporter: A lot of Nikki fans here. But the pediatric nurse is showing a different side of herself. I think Clare's threatened by me. Like I'm sick of it. Like I'm not going to walk on egg shells around her. If you were to be how you are in the house around him, like I don't see that warranting like a rose. You're not handing out the roses. It's okay. Reporter: Nikki may not care for Clare, but Juan Pablo can't seem to keep his hands off her. I like those lips. Reporter: So far Megan's in the lead with both Megan and peter choosing Nikki to win it all. Jeremy, who says he followed his gut, is in last place. Jeremy, you were so wrong. Reporter: As for who wins the bracket and who wins the final rose, we'll find out next week. For "Nightline" I'm Lindsay Janis in New York. I think I want to hold off on my bachelor betting and wait for March madness.
This transcript has been automatically generated and may not be 100% accurate.