THE CALL ITSELF was not unusual. In the seven years they'd played together, Jayson Tatum and Jaylen Brown had kept in touch over the summers. Mostly via text, but occasionally they'd run into each other somewhere after the playoffs had ended and before training camp began. They were teammates and colleagues, but not close friends.

Offseasons tend to feel very short when playoff runs are long. And people tend to give each other space during the offseason before coming back to try to climb the mountain together again.

Last summer was no different. The Celtics had played deep into May before losing a Game 7 to the Miami Heat in the conference finals in the most excruciating way -- with Tatum turning an ankle and Brown unable to pick up the slack -- after rallying back from a 3-0 series deficit.

It was the kind of loss that can tear a team apart. Especially a team that was about to get a whole lot more expensive, with Brown eligible to sign a contract to become the highest-paid player in NBA history and Tatum one year away from doing the same.

Both young stars seemed to sense the urgency. The Celtics had been patient with them, even as fans and media had not. But eventually, they both knew that patience would wane.

Brown picked up the phone and suggested they work out together. "We'd never really been in the gym [during the summer] together," Tatum told ESPN. "Maybe socially, but this was really just showing the maturation of us both, and just growing up."

Celtics assistant coach Sam Cassell helped arrange the workouts. Tatum's trainer, Drew Hanlen, ran them. Celtics great Paul Pierce lifted weights with them and sat in the stands at Harvard Westlake High School in Studio City, California, as the two pushed each other and cemented a bond that carried through one of the most dominant seasons in NBA history -- one that ended Monday night with the franchise's 18th NBA title with a 106-88 win over the Dallas Mavericks in Game 5 of the NBA Finals.

"I just think we had passed the phase where we'd both been All-Stars and been on All-NBA teams," Tatum said. "Not saying that s--- is not important, but we'd done it. And god willing, we'll keep doing it. But it was time to start sacrificing points or shot attempts or whatever to win and have the best team in the league."

NBA history is filled with partnerships that fizzled before the stars came together in the way Tatum and Brown did to win the championship this year. Shaquille O'Neal and Penny Hardaway. Gary Payton and Shawn Kemp. Kevin Durant and Russell Westbrook. Chris Paul and Blake Griffin.

Sometimes ego is what broke them. Sometimes it was just circumstantial. An opponent they simply couldn't beat. Untimely injuries. An organization that lost faith.

Tatum and Brown had experienced all of those factors in their first seven seasons together, except the last one.

The Celtics have made wholesale changes at every level as Tatum and Brown tried to grow into the players who could finally bring a championship back to Boston. But they never lost faith in their two young stars.

Brad Stevens has gone from coach to president of basketball operations. Ime Udoka was hired, then fired, as coach. Joe Mazzulla was hired as an assistant, then promoted to head coach. No fewer than three veteran stars were brought in to help mentor Tatum and Brown -- Gordon Hayward (2017-2020), Kyrie Irving (2017-2019), Kemba Walker (2019-2021) -- but failed to lead them to a title.

The only configuration left to try was simply to lean completely into Tatum and Brown as the leaders of the team, play a style to maximize their talents, and hope they'd grow enough to win.

"We were always good and talented," Tatum said. "The game needed to slow down. We got to the conference finals two out of our first three years, and it just seemed like we were all so much older than we actually are. Everybody was like, 'Oh, they didn't win it. They can't play together. They should trade him.' And I was always like, 'I just turned 26 and he's 27.'

"Nobody wanted to give us no time."

THE CULMINATION OF Brown and Tatum's partnership was there for all to see Monday night as they traded compliments on the championship dais and postgame news conferences. Brown said Tatum could've won Finals MVP. Tatum said Brown deserved it. They hugged as brothers, then lifted the championship trophy.

Stevens stood off to the side, watching it all unfold.

"It's what it's all about," Stevens told ESPN as he stood in a quiet hallway, celebrating with his family as the party inside the Celtics locker room raged on.

As Stevens outlined what lessons he'd take from this championship, former Celtics player Tacko Fall and his young daughter stopped by to ask the best place to get a car back to his hotel. Stevens stopped what he was doing to help him with the logistics.

"Listen, when we're all done in our time with the Celtics, as coaches, as players, all that's going to really matter is how we treated each other," Stevens said. "Nothing else matters. The banners don't matter because if you win banners and you don't treat each other well, then you never get together later. And the whole point is to have a reunion later."

More than anyone in the organization, Stevens is responsible for the decision to keep giving Brown and Tatum time to build their relationship and grow into the leaders of the franchise.

He was the coach who signed off on drafting each of them, then the executive entrusted with building the right team around them. He was the decision-maker on all of the trade offers that came in from around the league as teams hoped Boston would lose patience with one or both of them.

He was the man, sources said, who said no or decided not to pursue trades for Paul George (2017), Jimmy Butler (2018-19), Kawhi Leonard (2019) Anthony Davis (2019) and Kevin Durant (2022).

Occasionally, these trade discussions would become public, forcing Stevens to try to reassure Brown of the organization's commitment to him.

Tatum often wondered how Brown dealt with hearing his name in trade rumors.

"It would bother me," Tatum said. "Not talking from a pedestal, but I didn't necessarily know what that felt like. But I could just imagine all the hard work that he put in. I saw it every day. Even the strongest-minded person, that would affect you at some point. So I always felt for him in that regard.

"I think now that maybe I could have been better. I never said too much. I always have stayed out of that."

This offseason Stevens finally quashed all those rumors for good by signing Brown to the largest contract in NBA history.

"You worry about how some people would handle that," Stevens said. "Not Jaylen. He's a worker. He just wants to get better. He takes everything as motivation to improve."

Brown rewarded that faith by playing the best basketball of his career in these playoffs, being named the MVP of both the conference finals and Finals.

Occasionally he'd allude to the angst he'd felt in previous years, when he didn't come through on the biggest stage, or heard his name in trade rumors.

"I wasn't expecting it at all," Brown said after winning the Larry Bird MVP Trophy following the Celtics' sweep of the Indiana Pacers in the Eastern Conference finals. "I don't ever win s---."

But after he was named Finals MVP, Brown wasn't interested in using the platform to speak to those who'd doubted him.

"If you would have asked me that maybe a year ago, I would probably say yeah," Brown said. "But just at the point I got to right now, it feels great. Any of the personal awards, it is what it is."

What he was excited about was sharing the award and the moment with Tatum.

"Just our growth together," he said. "We've been through a lot. We've been playing together for seven years now. We've been through a lot, the losses, the expectations. The media have said all different types of things: We can't play together, we are never going to win.

"We heard it all. But we just blocked it out, and we just kept going. I trusted him. He trusted me. And we did it together."

TATUM'S 6-YEAR-OLD son, Deuce, is the physical embodiment of the journey his father has taken with the Celtics.

Tatum was a rookie when Deuce was born in December 2017.

He was just 19 at the time and had kept his impending fatherhood a secret from everyone in the Celtics organization until a few weeks before his birth.

"I was 19 and I was about to have a kid that nobody knew about," Tatum said. "He was born six weeks into the season and I was scared. I was like, 'I don't want to roll over on him ... We [Tatum, Deuce's mother and Tatum's mother, Brandy Cole] all lived in the same apartment building, but we all had three different apartments.

"I saw him every day, and I would come home every day after practice and we would take a two-hour nap on the couch every day together. I'd be burping him and feeding him and changing diapers and all that."

Brown was just 21 back then. And while he'd known Tatum in high school and played summer league together with him in Utah and Las Vegas, their lives were about to diverge.

"I mean I knew right away," said Irving, who was close with Tatum because of their connection to Duke. "I also had my daughter very young, so I knew how his life was going to change. He was scared s---less, just like I was as a father. No one's ready to have a child when they're still living out their childhood dream. But I've seen him grow so much. He's really a great dad."

Monday night, Tatum hoisted Deuce high in the air before he got to do the same with the Larry O'Brien Trophy.

Deuce told his father he was the "best in the world," to which Tatum smiled and said, 'You're damn right I am.'"

Just two years earlier, it had been Deuce who snapped Tatum out of the funk he'd been in since losing the 2022 Finals to the Golden State Warriors. Tatum was inconsolable. He'd turned his phone off and slept all day. He couldn't believe he'd run out of energy with a championship on the line and vowed never to let that happen again.

"I was just exhausted," Tatum told ESPN in 2022. "Mentally, physically. All the stress and pressure that I was putting on myself."

Deuce was the one who finally got his father up and out of the house by asking to go on their annual Father's Day trip to the Caribbean. But Tatum was forever changed by it.

He worked out every day that summer. He lifted weights instead of taking breaks to play golf. He trained with Hanlen to address the weaknesses in his game the Warriors had exploited.

Tatum shot 34% in the paint in the 2022 Finals, making it the worst mark by any player in a Finals over the past 25 years and the third worst by any player in any playoff series over the past 25 years among individuals with at least 50 shot attempts in the paint, according to ESPN Stats & Information.

This year he completely flipped the script, shooting 51% in the paint and 47% overall against the Mavericks. According to Second Spectrum, Tatum recorded a 58.3% blow-by rate on drives in the Finals, the second highest by any player in a series in the past 10 years.

"It took being relentless," Tatum said. "It took being on the other side of this and losing in the Finals and being at literally the lowest point in a basketball career that you could be, to next year, to the following year, thinking that was going to be the time, and come up short again.

"You know what it feels like to be on the other side of this and be in the locker room and hearing the other team celebrating, hearing them celebrate on your home floor. That was devastating.

"Now, to elevate yourself in a space that, you know, all your favorite players are in, everybody that they consider greats or legends have won a championship, and all of the guys I looked up to won a championship, multiple championships.

"Now I can, like, walk in those rooms and be a part of that. It's a hell of a feeling. This is more -- I dreamed about what it would be like, but this is 10 times better."

EVERY RETELLING OF Tatum and Brown's story will have some characterization of their personal relationship. Whether they always got along this well. Whether there was drama or jealousy behind the scenes. Whether they each believed the other was the right partner or had the right skill set to win together.

"The whole Jayson-Jaylen discussion in the national media is laughable to all of us," Stevens said. "I think Jaylen said it best with his line a few weeks ago where he said, 'I don't have the time to give a f---.'"

In the glow of victory, it's easy to color over all those questions. They are irrelevant now, because they won together.

Hanlen spent Monday morning flying back from working out a new client in Greece and thinking about what to text Tatum to inspire him to close out the title in Game 5. He looked up Michael Jordan's title in 1998 and Kobe Bryant's in 2010.

"I said to Jayson, 'What do you remember about that series? [Michael Jordan's] pull-up clincher at the end of Game 6, right? But do you remember that they lost Game 1? Do you remember that he missed a game winner? Do you remember? He was 9-for-26 in a Game 5 loss.

"All you remember was the game, the clinching pull-back game winner,"

"My big thing to him was, 'Hey, no one really cares what you did game by game. All that really matters is if you hang a banner."

Stevens has been in Boston for the entire duration of Tatum and Brown's partnership. His perspective is unique, having been their coach and now the team's lead executive.

"To me, teams thrive when there's little drama and they're moving in one direction," Stevens said.

The Celtics have had very little drama this season. They were the best team in the regular season with 64 wins. They went 16-3 in the playoffs, winning eight games by 15 or more points. Offensively they are among the best in NBA history, scoring 122.2 points per 100 possessions.

The 35-year-old Mazzulla is the coach of record for this season. Stevens hired him as an assistant coach just five years ago, a giant leap of faith in a guy who'd never coached above Division II in college or in the NBA.

But Stevens had faith in him immediately. He liked his dedication to his craft and discipline. He liked his analytical mind. But mostly he liked his passion.

"He may have been unproven to other people, but not to me," Stevens said. "He was put in a tough situation last year. But he grew from it, and this year he got a chance to really prepare for a season."

Mazzulla talks often about having a "growth mentality." He used the phrase last week when he was asked about Brown's development. He used it throughout the season when talking about how the team stayed sharp despite having such a huge lead in the standings.

Monday night he used the phrase when talking about how he starts each day in the cold tub at his house.

Thirty-nine degrees, not the relatively balmy 55 degrees of the tub in the Celtics' training facility.

"I started doing it for psychological growth," he said. "To purposely put myself in an uncomfortable situation where everything hurts and you have to learn about yourself."

Cryotherapy, Mazzulla said, is "too easy."

And when he really wants to challenge himself, he'll plunge under the water and hold his breath for 15-20 seconds.

"You have to stay in long enough," he said. "That's how you grow."