Since being acquired from the Suns in February, the 5-foot-9-inch point guard has been a revelation, helping improbably transform the Celtics into a playoff team. He has just completed a basketball clinic in this small gym, and now he will take questions.

About 100 children are packed into the bleachers at the Waltham Boys & Girls Club, as life-size decals of Tom Brady and Paul Pierce stare down from concrete walls. Isaiah Thomas is not a Boston sports icon like those two — as evidenced by the fact that a boy came to this event in a Rajon Rondo T-shirt — but he will strive to become one.


One student asks Thomas what elementary school he attended. Another asks about his nationality. The moderator pleads for more depth, and a young girl raises her hand.

“Have you ever thought about quitting?”

The question seems to catch Thomas off guard. He fiddles with his hands and sways.

The students don’t know how dejected he was at prep school, to the point where he lied to his coach about family events just to fly home. They don’t know that people used to try to fight him simply because they could not handle losing a basketball game to a pipsqueak. They don’t know about the tears on NBA Draft night, when his future went from promising to uncertain in a few stressful hours.

“Quitting?” Thomas says. “Nah, I’ve never been a quitter.”

. . .

One summer day about 12 years ago, NBA veteran Jason Terry was at his father’s home in Tacoma, Wash., when he heard a constant thumping outside. Terry, then a young guard for the Hawks, found a small boy shooting baskets alone. The boy told Terry he was friends with his younger brother, Curtis, so Terry shrugged and went back inside.


“Then it’s like 10 p.m., and I hear it again,” Terry recalled, his voice rising. “I go back out, and Isaiah is still out there shooting all by himself.”

Most people close to Thomas have similar basketball stories. The time he secretly stuffed his way-too-big Lakers jersey into his backpack and slipped it on for school pictures. The time his teacher contacted his father, James, because Isaiah refused to come in after fourth-grade basketball recess, and Isaiah explained that he could only improve his game against the sixth-graders.

“Even when he was a toddler,” James Thomas, said, “he would just carry that basketball around like Linus carried his blanket.”

In middle school, Thomas rode city buses around Tacoma in search of the best games the way surfers search for the best waves. If the gym required a membership, he would try to sneak in — perhaps a perk of being pint-size.

He was initially bothered by his height. He used to hang from a chin-up bar at his home, hoping it would stretch his body like taffy. When he had physical exams, his mother, Tina Baldtrip, asked the doctor not to predict how tall he would be. But sometimes Isaiah would ask and get an answer, then sob all the way home.

But by ninth grade, he realized his height would not crush his basketball dreams. It just made him different. He wanted to become the best under-6-foot basketball player there ever was.

Isaiah Thomas (right) and his father James. Courtesy Thomas family

. . .

The legend of Isaiah Thomas spread quickly in the Pacific Northwest. His coach at Curtis High, Lindsay Bemis, was once approached by a coach from Portland looking for “the little Mighty Mouse” he had heard about. Jason Terry’s father used to coach Thomas’s AAU team and call Jason to recite his dazzling performances.


“I’m like, ‘Little Isaiah who used to be shooting on the goal in the back?’ ” Jason Terry said. “And then he’d tell me he just scored 50 the other day. Fifty!”

Clippers guard and Seattle native Jamal Crawford, who played for the Knicks at the time, heard stories about Thomas, too. He heard about him pouring in 52 points in a game at Key Arena. He heard about him lighting up opponents twice his age and twice his size in pickup games.

The two became friends, and Crawford asked Thomas to join his summer league, which included players such as Crawford and Terry as well as hardened Seattle street-ball stars whose dreams had fallen short.

“And Isaiah was just killing people,” Crawford said, “as a high school student.”

Thomas accepted a scholarship to the University of Washington, but there were concerns he would not qualify academically. In late fall of his senior year, he begrudgingly enrolled at South Kent School — an all-boys preparatory academy tucked in the hills of Connecticut — and reclassified as a junior.

“When that happened, people in Tacoma didn’t think I’d ever make it to college,” he said. “They thought that was it for me.”

. . .

South Kent was 3,000 miles from Thomas’s home, and it felt even farther. He arrived during a cold, gray winter and struggled with the rigid lifestyle: The tie-and-blazer dress code, the mandatory chapel sessions, the curfews. Thomas called his mother almost every night and asked if he could come home.


“At 16, going across the country to a place I didn’t know, away from my family, was the toughest thing I’ve ever had to do,” he said. “There were times I just wanted to give up and leave.”

And there were times he tried. He once told coach Raphael Chillious that he had a family wedding to attend. He returned to Tacoma, where there was no wedding. Chillious suspended Thomas for three games.

Basketball was his only outlet. He would go to the gym at 6 a.m. and return there most nights, either by himself or with a freshman who would rebound for him.

Since Crawford was playing for the Knicks, Thomas often took the one-hour train ride to his White Plains home on weekends. They would watch games and play one-on-one on the lighted outdoor court long past sunset. When Thomas went to Knicks games at Madison Square Garden, he was there as a student.

“I watched everything they did,” he said. “How they walk, how they talk, how they carry themselves.”

He came to view South Kent as a necessary step, and he began to thrive. By his final year, he was the one telling scared underclassmen how they would succeed, how it would all be worth it.


. . .

At Washington, Thomas was in command from the start. He led the Huskies to three Pac-10 titles and earned all-league honors each time. His competitive fire was obvious.

In the second round of the 2010 NCAA Tournament, the Huskies trailed Marquette by 15 points with 13:51 left. Darius Johnson-Odom was torching them, and Thomas was furious. During a timeout, he demanded to defend Johnson-Odom. The Marquette guard did not score another basket, and Washington won, 80-78.

“To me,” Huskies coach Lorenzo Romar said, “that just summarized Isaiah’s whole being on the basketball floor.”

In Thomas’s junior year, Washington was in a close game at Washington State. There was a late timeout and Thomas needed to use the bathroom, but he worried that if he left the game he might not return in time. So he asked for a towel and told his teammates to encircle him.

“He put the towel in his shorts and peed on the bench, because he didn’t want to check out,” said Chillious, who became an assistant at Washington. “That was a guy who wanted to compete.”

Even though almost everyone in Thomas’s inner circle encouraged him to return to school for his senior year, he declared for the 2011 draft.

“Everybody was like, ‘What are you doing?!’ ” he said. “But I had my mind made up.”

Isaiah Thomas has played in 21 games for the Celtics since being acquired in a trade with the Suns. Getty Images

. . .

Basketball Hall of Famer Isiah Thomas, who befriended Isaiah in part because of their obvious similarity, was working as an advisor for the Knicks at the time. He thought Thomas had first-round talent, and he recommended that the team attempt to acquire him. Jason Terry, meanwhile, sat in on Thomas’s pre-draft workout with the Mavericks.

“It was one of the most phenomenal workouts I’ve ever seen from a guard,” Terry said. “He dominated. There was no doubt in my mind Dallas would pick him.”

Ultimately, though, the Knicks wouldn’t pick him, the Mavericks wouldn’t pick him, and it was unclear if anyone would pick him.

Thomas and his future fiancé, Kayla Wallace, invited 40 friends and family members to their apartment for the draft. They rented tables and chairs and served chicken, macaroni and baked beans. It was a party.

Isaiah was anxious, though, so he went to Washington’s gym to shoot baskets, occasionally checking his phone for updates. The first round passed, then the second round began to speed by.

Back at the apartment, the buzz had faded. People had trickled out of the viewing room. Thomas’s father went outside, into the rain, and prayed. Some family members began to cry.

“I started to worry, like, if this doesn’t happen, what direction is this party going to go?” Wallace said. “And what is our Plan B?”

Finally, with two selections left, Thomas received a call from his agent that the Sacramento Kings would take him with the 60th and final choice. Now the tears were joyous. James Thomas pulled his son close.

“That’s all we wanted,” he told him. “All we wanted was a chance.”

Isaiah Thomas (left), with his sons, James, 4, and Jaiden, 3, and fiancee Kayla Wallace. Courtesy Thomas family

. . .

Thomas was not guaranteed a roster spot as a second-round pick, so he attacked training camp. The Kings actually contacted the Washington coaching staff and asked for advice on how to get Thomas to calm down.

“They said he was sprinting to get water during breaks, sprinting back to the court, going hard the entire time, and it was almost making the veterans look bad,” Chillious said. “So we called Isaiah and said, ‘Hey, keep it up.’ ”

Thomas made the team, entered the starting lineup in the 27th game and stayed there. He was the Western Conference Rookie of the Month in February and March.

“When I was out on the floor,” Thomas said, “I wanted to make people be like, ‘Man, why isn’t that guy playing more?’ ”

Last year Thomas averaged 20.3 points and 6.3 assists per game. Three seasons after simply hoping to be drafted, he entered the open market in control.

At 12:01 a.m. on July 1, the first day of free agency, Celtics president of basketball operations Danny Ainge called. He told Thomas he admired him and made it clear he wanted him to become a Celtic, even if not now.

Thomas visited Phoenix first, and the Suns wooed him. He was on the cover of a media guide wearing their uniform. At the arena, he was superimposed on a large billboard. His sons James, 4 — from a previous relationship — and Jaiden, 3, received personalized Phoenix jerseys. And, of course, he was offered a four-year, $28 million deal.

The Suns sold the idea of joining an offense with point guards Eric Bledsoe and Goran Dragic. Thomas called Terry, now a Houston Rocket, for advice.

“You just hit the lottery,” Terry told him. “It’s perfect.”

Thomas bought a house for his mother and a car for his father. He was living his dream. But as this season unfolded, it was clear there was not room for all three guards.

“I was taking a step back,” Thomas said. “We all wanted the ball and are all talented, but somebody ended up upset every night. It’s something that everyone thought would work, but it just didn’t.”

Isaiah Thomas played 46 games with the Suns this season. AP

When Dragic requested a trade and was sent to the Heat, it seemed the problem had been resolved. The team was on its bus before leaving for the airport on Feb. 19 when the 3 p.m. trade deadline hit. Then forward Brandan Wright saw on his phone that Thomas had been sent to the Celtics; a Suns employee verified it minutes later.

Thomas grabbed sneakers from his locker and drove home in a daze. He ignored the calls and text messages that were flooding in. He didn’t want to uproot his family or leave the warmth of Phoenix for Boston, which was in the midst of an historically brutal winter. He felt like it was South Kent all over again.

Then he noticed a text message from Isiah Thomas, the Hall of Famer, and his outlook began to shift.

“This is gonna change your career,” it said. “They’re one game out of the playoffs. Lead them to the playoffs.”

Thomas flew to Boston the next morning. He FaceTimed with coach Brad Stevens and watched the Celtics’ game against the Kings on television with Ainge, who told him that if he embraces his role, he could become a legend.

“If that’s the truth, I’m down for that,” Thomas told Ainge. “I want that type of pressure.”

. . .

James Thomas is sitting in his second-row seat behind a TD Garden basket, sipping a beer from a clear plastic cup. LeBron James is on the Cavaliers’ bench about 20 feet away.

The Celtics are on their way to another win, on their way to a playoff berth, and it is a perfect day for Thomas to see his son in a Celtics uniform for the first time. Thomas, who has worked as a parts inspector at Boeing for 26 years, smiles and points to the collection of banners hanging from the rafters.

“This,” he says, “feels like a championship place.”

Isaiah Thomas is averaging 19 points and 5.4 assists and is a leading Sixth Man of the Year candidate. His mother, who still works as a hospice nurse in Tacoma, says that when she sees her son on television now, she can tell he is happy again. He is the headliner of this team and he loves this city, even if it does not feel like home yet.

Isaiah Thomas 2014-15 stats Games Starts Minutes PPG APG Phoenix 46 1 25.7 15.2 3.7 Boston 21 0 26.0 19.0 5.4 SOURCE : NBA Globe Staff

Thomas has been living at the Hyatt House hotel in Waltham while Wallace helps prepare the couple’s new offseason home in the Tacoma area. They will look for an apartment in Boston this summer, but for now, Thomas is usually here alone, eating breakfast by himself at In A Pickle restaurant and then heading to the training facility to workout.

His two boys are living in Washington for now, too, and they are confused. They just know their father plays for the green team, and they still think he is most famous for being on commercials for the “Pizza Guys” franchise back in Sacramento.

In Phoenix, Isaiah used to wake up each morning — even after returning from road games in the wee hours — and take Jaiden and James to day care. He misses them terribly, and this week he begged Wallace to bring them out to see him.

And so they are here at the Cavaliers game. They raise their arms and yell when Isaiah’s name booms over the public address system after he drains a 3-pointer. And this time, about 20,000 other people join them.

“I think this city will love Isaiah, because he fits with its mentality,” Wallace said. “He’s a fighter, a hard worker, and he wants to have an impact.”

Related coverage:

■ Celtics-Cavaliers playoff schedule

■ Brad Stevens named NBA coach of the month

Adam Himmelsbach can be reached at adam.himmeslbach@globe.com. Follow him on Twitter @adamhimmelsbach.