Boston fans still send No. 4 Celtics jerseys to his Denver Nuggets address, and he still signs them and sends them back. He still talks to most team staff members, including coach Brad Stevens, about once a month. He still logs on Twitter and Instagram and notices that the vast majority of the messages are related to his fleeting but fabulous time as a Celtic.

The Celtics traded Isaiah Thomas away nearly two years ago, but his connection to this team and this city endures.

“What happened in Boston happened for a reason, and that love’s going to last forever,” Thomas said in a phone interview Sunday. “I was only here three years, but you’d think I was here 15 from the love that they showed me and the love that we gave each other. That’s all genuine. It was a city that needed something at that time, and I needed a team that believed in me. I’m a hard-working guy and played with my all, and that’s all the people here wanted. They expected greatness, and I wanted to show them greatness.”

On Monday, Thomas will return to the Garden as an active player for the first time since he was sent away in the deal that brought Kyrie Irving to Boston. It is impossible for him to look at this loaded Celtics roster — including players like Al Horford and Gordon Hayward, who came here in part because they wanted to play with him — and not think about what could have been.


“We were building something special, and the world knows that,” Thomas said. “But stuff happens. I got traded. Everyone moved on.”

Still, Thomas said the memories he crafted in Boston are what he truly cherishes. He came here in February 2015 as a little-known sparkplug who could come off the bench and score points. He left two and a half years later as a two-time All-Star who averaged 28.9 points per game in his final season and caused fans around the world to suspend belief about what a 5-foot-9-inch point guard might be capable of.


“I’ll remember how the city treated my family, how ever since I came here, it was special to me,” Thomas said. “So this will always be home, this will always be like how [my hometown] Tacoma feels to me. It’ll always be something that’s bigger than basketball here, and I can’t thank this city and organization enough for that.”

Thomas said that beyond the big games and big wins, the connection he formed with Boston during his lowest times remains most important. The day before the Celtics opened the 2017 playoffs, Thomas’s younger sister, Chyna, was killed in a car crash. Thomas played despite the pain, but he never felt alone as he did.

“That’s probably the biggest thing for me, how this whole organization and city came together with me and were by my side when I grieved,” he said. “The love and what I feel for Boston will never change because of that.”

Later in those playoffs, Thomas had several teeth knocked out in a conference semifinal game against the Wizards. He underwent major dental surgery and returned for the next game. Then in Game 6 of that series, he aggravated a March hip injury before ultimately reaching the point after Game 2 of the conference finals against Cleveland that he could play no more.


Thomas initially bypassed surgery, and while he was rehabbing in August he was traded to the Cavaliers. Thomas was stunned and hurt and angry, and those feelings intensified as his hip injury lingered and last season was washed away as Boston charged to the brink of the Finals without him. But over time, Thomas came to peace with it.

“I was hurt, yeah,” he said. “I still think it was messed up. But at the end of the day it was a business decision by a businessman, which I understand. I just feel like how it went down, I was hurt by it. But time heals all, and time healed that. I’m not holding no grudge on anybody. That’s just not who I am.”

When Thomas became a free agent last July, he called Celtics president of basketball operations Danny Ainge to float the idea of a return.

“I know we left on bad terms with me being traded,” Thomas said. “I wanted them to know that the interest was there. I didn’t know if they were interested, and I wasn’t saying I wanted to come back and be the guy. I was just saying if the opportunity presents itself, just know I’m interested. That’s all it was.”

Thomas said that Ainge told him at the time the Celtics were primarily focused on re-signing Marcus Smart, which they ultimately did. But Thomas will be a free agent again this summer, and perhaps this opportunity will present itself once more.


“You never know,” he said. “You can’t predict the future. My options are always open for anybody. I’m a Denver Nugget now, but I’m a free agent at the end of the season, and you never know what can happen. Who knows?”

When Thomas returned to Boston with the Cavaliers last season, there was some controversy surrounding the tribute video the Celtics planned to show for him. Thomas requested that the video be postponed until he came back for a game in which he was playing, but the Cavaliers’ second game in Boston was also on the day Paul Pierce’s No. 34 was being retired. Pierce ultimately spoke out against Thomas being honored that day, many fans sided with Pierce, and Thomas ultimately relented. Then he was traded again and has not been back since.

This time, there has been no real buzz about how Thomas will be honored. He said the Celtics had not reached out to him about it.

“If they don’t do anything, it’s still all love,” Thomas said. “If they do, it’d be cool, too. It’d be dope, because I put my heart, sweat, and tears, everything I had on that Garden floor for this organization. But I’m not expecting it.”

Thomas, who underwent hip surgery last March, made his Nuggets debut on Feb. 13. But he has struggled in limited action, averaging 8.6 points and 1.7 assists on 37.3 percent shooting.


He acknowledges that he has not had the start he was hoping for but he said he feels healthy and ready.

Nevertheless, Thomas has been removed from the Nuggets’ regular rotation and has not appeared in the last three games. Denver sits one game behind the first-place Warriors in the Western Conference, and coach Mike Malone has tightened the rotation.

“It’s tough, but all I ask for is an opportunity,” Thomas said. “I know once I do get the opportunity I’ll be able to do the best I always have. I’ve just got to be patient though and wait for my turn. Whatever this team needs me to do, that’s what I’m here to do. I just would love to show people I’m healthy, because I think that was the biggest question out of all things: Is he healthy?”

Malone might realize the significance of Thomas’s Boston return on Monday, or he might just move forward with business as usual. Thomas said he had not spoken with Malone about playing Monday, and that he would not bring it up.

“I know [the atmosphere] is probably going to be crazy,” Thomas said. “The fans are going to want to see me play. I’ve always been a guy like, ‘I’m going to show the people what they want.’ But at the end of the day, it’s Coach’s call. But if he calls my name, I’ll be more than ready.”

Adam Himmelsbach can be reached at adam.himmelsbach @globe.com.