CLEVELAND -- Mike Clevinger compared their relationship to that of brothers. In many ways, Trevor Bauer and Clevinger are nothing alike, but there is a competitive fire that unites them and has helped forge a friendship that would seem improbable on the surface.

"He wants to throw harder, better, sharper every day. And that's what I want to do," Clevinger said. "Hold on ..."

The Indians pitcher stopped mid-thought on Wednesday morning and grabbed his wallet from a ledge near his locker inside Cleveland's clubhouse at Progressive Field. He opened the large pocket and pulled out a worn and wrinkled $100 bill that has been stuffed in the folded leather for the better part of two years now.

"We can put this on record now," Clevinger said.

Two springs ago, Clevinger and Bauer made a simple bet: $100 to the pitcher who had the highest fastball velocity reading in their first live batting-practice session. Bauer rolled his eyes when noting that Clevinger came out on top by "point two or something," but that was enough. So he retrieved the bill, grabbed a Sharpie, wrote, "To Daddy Velo, you win," to the right of Benjamin Franklin's image, and sealed it with an autograph.

Clevinger smiled while examining the note again, still savoring the annoyance Bauer must have felt at the time.

"I keep that on me everywhere," Clevinger said. "If he ever wants to chirp, I've got that in my back pocket -- literally."

For the bulk of Bauer's career in Cleveland, the right-hander has seemingly trained in isolation. Tribe starters have monitored each other's bullpen sessions for instant feedback sessions for a couple of years now, but the day-to-day work for Bauer has typically been on his own. Since Clevinger has come into the fold, Bauer has gained a regular training partner.

Part of that is schedule-based -- their place in the rotation and between-start routines align well for long-toss sessions, weighted-ball work and regular catch -- but it is also due to their growing bond built upon brotherly competitiveness. Clevinger was among the people in Bauer's ear last season about adding a slider. Bauer has helped Clevinger fine-tune his mechanics and throwing program.

"I'm actually encouraged to talk to my teammates and share information this year," Bauer said. "That had been discouraged in the past at times. That's been super refreshing this year."

In the process, both Bauer and Clevinger have been enjoying breakout seasons.

Bauer has a 2.50 ERA with a team-leading 129 strikeouts in 100 2/3 innings, and currently ranks fifth in the Majors with 3.6 WAR (per Fangraphs). Clevinger, who opened the season in the Indians' rotation for the first time this year, has a 3.00 ERA in 99 innings while ranking 11th overall in pitcher WAR (2.3). Bauer (109.3) and Clevinger (104.1) rank first and third, respectively, in the Majors in pitches per game.

"They talk, probably more those two than the other guys and I think it's a good thing," Indians manager Terry Francona said. "I think it's a good thing if they can feed off each other. They can learn and that's important."

On Tuesday night, Clevinger was not feeling right on the mound early on in his outing against the White Sox. When he headed back into the Tribe dugout after a tough first inning, he checked in with Bauer.

"He told me, 'You're sitting on the rubber. You're just sitting there. You're not moving,'" Clevinger recalled. "He's like, 'Don't think about other [stuff]. Don't think about your arm. You need to move to the plate. Everything's in the right spot. You just need to move faster to the plate. You're being sluggish.'"

The White Sox went 3-for-23 the rest of the way against Clevinger, who picked up the win.

"A little key like that," Clevinger said, "a little direction and that turned that start around for me completely. He's done that with me probably two or three starts this year. Some little key and ..."

Clevinger snapped his fingers.

"Next thing you know it's like, 'Bam, bam, bam.'"

Looking at Bauer and Clevinger, it would be hard to envision them as fast friends.

Clevinger's hair is wild and to his shoulders. Bauer's close-crop cut is the low-maintenance look of someone with other things to worry about. Clevinger looks like someone who traveled through time from the '60s with his colorful tattoos, creative outfits and affinity for Jimi Hendrix. Bauer often sports a plain T-shirt and jeans. Clevinger pitches like a wild horse trying to be restrained. Every movement by Bauer seems calculated.

Still, there is actually common ground that exists there.

"I know for a fact there's judgment on both of us from outside sources," Bauer said, "based on how he lives his life or what I choose to say or what I do or what he whatever. It's both probably cases of judging a book by its cover before you get to know us and understand what makes us tick. I'm not about that and he's not, either. So it's easy. It makes for an easy connection."

There is also a shared love for science -- just in different capacities.

"I wanted to be a biologist. That was my thing," Clevinger said. "I love facts that can help answer why life revolves, evolves, et cetera. I like those facts. He likes facts and numbers, the science behind pitching with numbers and statistics. And then we both just have that competitive nature."

That common trait lends itself to some brotherly feuds, too.

This past spring, some of Bauer's weighted baseballs kept going missing from his locker. He discovered that Clevinger kept borrowing the training tools, but the righty would forget to put them back. In retaliation, Bauer went into Clevinger's locker and took his hacky sack.

"He was all mad and wouldn't talk to me," Bauer said.

Clevinger fought back.

"He had two books shipped to my locker," Bauer said with a smirk. "One was like, 'It's not all about me,' and the other one was, 'How to Be a Good Teammate,' or something."

Bauer then ordered a weighted-ball set and left that on Clevinger's chair as a truce.

"There's times I want to wring him up by the neck and I'm sure he feels the same way about me," Clevinger said with a laugh. "There's times we've yelled at each other, gotten in each other's face. And there's times we've hugged it out and laughed about it. It's been like a tug-o-war, but it's just that competitive nature."

The $100 bill is evidence to that end, though Bauer notes that Clevinger would not participate in a similar bet this past spring.

"I tried to. He said no," Bauer said. "He knows that I throw harder than he does now."