A return to a hostile Boston was looming on Monday after his Dallas Mavericks had trounced the Celtics in Game 4 of the NBA Finals. Just a few days earlier, he had teased that there were things no one knew about during his rocky two-year stint with the team that now stands between him and his second championship.When I asked him if he'd be willing to detail what those things were, he agreed. In fact, it's something he wishes he had done much sooner."I would have loved to write a letter if possible, to not only the fans of Boston, but to the people in the organization, so they get a better understanding," Irving told FOX Sports.Irving thinks of Boston fondly. Celtics fans view him as a traitor. He wants to bridge the disconnect.Irving, who played for the Celtics from 2017-2019, has been the target of fans' ire ever since he publicly announced he was going to re-sign with the team in October 2018 then, eight months later, left for Brooklyn.

But right after he made that commitment, he received a devastating blow."A week later, I lose my grandfather," Irving told FOX Sports. "That was one of the hardest points in my life just because I didn't know how to move forward, not just with my career in Boston. But just my career in general."I had never lost somebody in the middle of the season before, or the start of the season. It's my mom's father, so it was tough on me emotionally. But it was more tough on me to find joy in the game of basketball again."Irving felt lost that season. He withdrew from his teammates. He didn't know how to talk about his grief.

His grandfather held a special place in his heart and represented a connection to that side of his family, especially since his mother had died when Irving was 4.

"He was a huge supporter," Irving told FOX Sports. "He used to bring hundreds of people to Portland [the closest NBA city to where his grandfather lived in Seattle] to come and see me. [He] really helped me get in touch with my native roots, where my mom was from and my tribe [the Standing Rock Sioux Nation in North Dakota]. So, he was more of a guiding light for me. And he was a pastor of a church, a big congregation, was loved by the community. He was the opposite skin color of me, as well, which was the beautiful thing about our family dynamic.

"I have so many different walks of life, culturally, religiously, racially in my family. So, for me, growing up with him, it gave me a very different perspective of the world. And he allowed me to ask questions and stay curious. He would always put me in my place, too, if I didn't put God first. And he helped me realize the big picture of life, about faith and making sure you help people. He did a lot for me."Irving sank into a depression.In Irving's first season with the Celtics, they had flown to a 16-2 start before an injury sidelined him for the stretch-run and postseason. The following season, after his grandfather died, things changed. His leadership skills were questioned. He was considered mercurial.He shined on the court, averaging 23.8 points, 6.9 assists and five rebounds. But behind the scenes, he kept to himself and a Celtics team that was expected to compete for a championship later collapsed in the second round of the playoffs.

"When I lost him as the guiding light in the physical world, basketball was the last thing I was thinking about," Irving told FOX Sports. "And then being in a historic place like Boston, it was hard to explain to people that I was dealing with that. Hard to talk to my teammates about it. I didn't know how to talk about it. So that's what I was really referring to."I don't think a lot of people cared about how I was doing as a human being. Because here I am as this staple in the NBA. I'm the No. 1 pick. I have a lot of pressure on me. I'm in Boston. I had just committed back to them. And now, the only thing I'm really thinking about is being there for my family, which is why I went back to Brooklyn. I couldn't stay in Boston to fulfill some of those responsibilities because my family was hurting, too. So, I took on the burden of being a man of my family, going back to New York."Irving said that around that time, not only was he dealing with the loss of his grandfather, but he was trying to find his way as a young father after his daughter's birth in 2015.

When it became clear he was going to renege on his pledge to return to Boston, he and Kevin Durant schemed to join forces in Brooklyn. But then another wrinkle was added to an already emotionally trying time: Durant suffered a devastating Achilles tear while playing for Golden State in the 2019 NBA Finals, shortly before free agency.Irving said that deeply weighed on him, too."I took on one of my best friends who had just torn his Achilles in the Finals and trying to be there for him as a human being," Irving told FOX Sports. "I don't know how many people would still commit to going somewhere after their friend or peer just tears his Achilles, and you don't know if they're going to come back. So I felt even more called to be there for him."Regardless, Celtics fans felt left in the lurch.

And things have been hostile between the superstar and his former fan base ever since.When his Nets met the Celtics in the first round of the 2021 playoffs, Irving famously stomped on the Boston logo at midcourt after their win in Game 4. As he walked off the court, a fan then threw a water bottle at him, something he said gives him a "traumatic response" whenever he's back in that environment, as he will be on Monday.The following postseason, when the teams met again in the first round of the playoffs, he gave Celtics fans the middle finger twice in Game 1, once after hitting a 3-pointer and then again with both hands as he inbounded a ball in the fourth quarter. It's no surprise things have also been tense during these Finals.Before Game 1, fans stomped on a blow-up doll with a picture of Irving's face on it outside of the arena, as they chanted, "F--- Kyrie." In Games 1 and 2, the crowd would boo loudly and chant "Kyrie sucks" whenever he'd touch the ball. And when Irving said after Game 1, "I thought it was gonna be a little louder in here," his quote was displayed on the video board in Game 2 as fans screamed.Meanwhile, it appeared as though Irving poked Celtics fans by wearing pants with a shamrock emblazoned on his seat during NBA Finals Media Day. But when questioned about that, he was genuinely confused."It's probably Guillermo who put it there," Irving said, referencing Guillermo Rodriguez, a sidekick for "Jimmy Kimmel Live!" who famously does quirky interviews with players on Media Day. "I think somebody brought up that I had a shamrock on.

I had no idea. Somebody brought it up and I was like, 'Okaaay?' ...People are staring at my butt. Damn, I'm at a whole new level now."With the Mavericks facing elimination trailing in the series 3-1, Irving is steeling himself for another harsh reception during Game 5 in Boston. He struggled there in his first two games of the series, averaging just 14 points on 35.2% shooting, before exploding for 35 points on 46.4% shooting in Game 3 in Dallas.Irving is going to try to block out the noise this time around. "Just figuring out how we come together more as a group and not just make it about me," Irving told FOX Sports.

"They're gonna chant. They're gonna do whatever they're going to do. But my focus has always been on playing the best basketball that I can for my teammates."For Irving, it's a shame his tenure with the Celtics ended so bitterly, especially considering he has a lot of love for the city. It's where his father, Drederick, played college basketball at Boston University. It's where he attended skills camps. It's where his parents met. It's where he shined on the court, further establishing himself as one of the top guards in the game.Irving regrets how he handled things five years ago.

He was overcome with emotions. He said he didn't have the mental maturity to compartmentalize things. He knows he let people down.But he also wants others to understand where he was coming from.So, if he could go back in time, he'd pen a heartfelt explanation to a city and a team that embraced him with open arms before things soured."When I look back on it, that's probably something I could've done," Irving told FOX Sports. "Just speak on why I did what I did instead of waiting years to come out and say it. But I needed to learn the vocabulary."Melissa Rohlin is an NBA writer for FOX Sports. She previously covered the league for Sports Illustrated, the Los Angeles Times, the Bay Area News Group and the San Antonio Express-News. Follow her on Twitter @melissarohlin.