Everyone has a different memory — a moment when they could first forecast Kyrie Irving’s greatness.

To some, it was as simple as his relentless work ethic. Others, a sterling high school performance. Or AAU dominance. Carrying a nondescript private school to a state title. Or staying up all night in his backyard shooting and dribbling. Overwhelming a powerhouse opponent.

But it all goes back to one simple constant about the Nets’ new point guard from West Orange, N.J., who starred first at Montclair Kimberley Academy and then St. Patrick High School.

“Basketball,” close friend Kevin Philemon said, “was his identity.”

“Like Picasso had painting, Jay-Z had rapping, basketball was Kyrie’s thing,” added Jhamar Youngblood, a former St. Patrick player.

From a young age, basketball was Irving’s life.

Philemon would often stay over at Irving’s house, and rarely get much sleep. The basketball would never stop, Irving shooting and dribbling until the sun came up. It was like pulling teeth to get him to go to the movies or attend a party.

As a kid, Irving would go with his father, Drederick, to a Boston University basketball camp, and former coach Dennis Wolff’s most vivid memory is Irving always being in the gym from 8 a.m. until 8 p.m. When the college guys played pickup, he would be shooting on the other court. At St. Patrick, he spent hours upon hours on different layups and spins off the backboard, perfecting the craft that has made him into one of the NBA’s best finishers.

“He just always seemed like he was a professional,” Youngblood said. “That’s what made him different from everybody else.”

A lot of that was in his upbringing. Drederick, once the all-time leading scorer at Boston University who played overseas in Australia, raised Kyrie and his sister, Asia, on his own after his wife, Elizabeth, passed away when Kyrie was 4. He would take his son to his pro-am games in a stroller.

At 13 months old, Kyrie dribbled the ball for the first time. In the fourth grade, he wrote that his goal was to reach the NBA after watching the Nets play in the finals.

Father and son would train together and the demanding Drederick coached him through the eighth grade. That’s when Kyrie met Sandy Pyonin, an AAU coach with the New Jersey Roadrunners and an accomplished trainer.

They would spend up to five hours a day at the YMHA in nearby Union, sometimes just the two of them. The workouts were intense, including full-court one-on-one games up to 100 — by one. Where other kids’ minds wandered and lost focus on occasion, that was never a concern with Irving. He always wanted to do more.

“You had to tell him to leave the gym,” Pyonin said. “He was a gym rat. He wanted to work until he was exhausted.”

More than a decade later, Irving remains a legend at Montclair Kimberley, a private school in northern New Jersey known for academics he transformed in his two years there. Drederick was looking for a school his son could play at right away and had strong academics, and Montclair Kimberley fit that mold.

He entered as an unknown, a 5-foot-8 “scrawny” kid, teammate Charles Bozik recalled, and by the time Irving left, he had begun to make a name for himself, and had grown to 6-feet.

“He made our team ridiculously good — better than we had any right being,” Bozik said.

He took a massive jump from his freshman year to sophomore year, doubling his scoring output. That season, he averaged 26.5 points, 10.3 rebounds, 4.8 assists and 3.6 steals. Irving scored 48 points in one game and 47 in another, the two highest totals in the state that season. Montclair Kimberley won its first — and only — New Jersey Prep ‘B’ state title that season. In the semifinals, he defeated Solomon Schechter, coached by Pyonin, on a buzzer-beater.

“They threw the whole team to stop him and he made [the shot] over three guys,” classmate Giri Nathan recalled.

Irving immersed himself in the close-knit community, frequently shooting around with classmates before practice after school. He handled the school’s rigorous academics and those who knew him said he never considered himself better than anyone else, despite his obvious talents.

“People liked spending time with him,” Nathan said.

Basketball games became social events, just to watch Irving play. A special rooting section was formed. Montclair Kimberley coach Tony Jones will still routinely get asked what it was like to coach him. Bozik once pump-faked Irving in practice and scored on him, a moment he calls his greatest achievement in life. The next time down court, after warning in a joking manner it would never happen again, Irving swatted Bozik’s shot out of bounds.

By the end of his sophomore season, it had become apparent Irving had outgrown the school. His passes would routinely hit the team’s big men in the stomach or bounce off their hands.

“He was faking me out and we were on the same team,” Bozik said.

Added Nathan: “My main memory was him being so many levels removed from everyone on the floor. It was just fun for us to be a part of. We knew that it wasn’t going to last too long.”

Despite Irving’s accomplishments at Montclair Kimberley, doubts remained, Philemon recalled. There were detractors who scoffed at the opponents he faced, questioned whether he could replicate that at St. Patrick, a state powerhouse developing into a national program full of premier recruits.

Irving, in fact, wasn’t even sure himself. Kevin Boyle, then the St. Patrick’s coach, recalled him deferring at first, out of respect for his teammates. Boyle and Irving had numerous talks that first season about what he wanted from his point guard, needing him to be aggressive, not always looking to pass to star teammates like Michael Kidd-Gilchrist and Dexter Strickland.

“He didn’t realize how good he was,” Boyle said.

That belief skyrocketed in an early-February game at Rutgers. St. Benedict’s Prep was ranked third in the country and St. Patrick hammered them. Irving was the star, scoring 21 points in three quarters, dominating a team that featured several future Division I players. After the game, Boyle told reporters Irving would be the best guard to ever come out of New Jersey.

“It was like an escalator going up, up and up after that game,” he said.

Irving led St. Patrick to a 30-3 record and the New Jersey Tournament of Champions title that year.

The summer before Irving’s senior year, Boyle was convinced of the star guard’s future. He entered his high school team into a national AAU showcase in Florida. But it didn’t have two of its best players, Kidd-Gilchrist and Derrick Gordon. After initially playing with his AAU team, Irving joined St. Pat’s for the quarterfinals. The Celtics were, on paper, major underdogs, facing Team Final and All-Ohio Red, two of the best AAU programs in the country. St. Patrick won both games, led by Irving and a group of role players. He hit 38 free throws in a row in the two games, owning the stage in front of hundreds of college coaches.

St. Patrick was banned from the state tournament Irving’s senior year for holding practice prior to the permitted start of the season, and the Celtics still went 24-3, with Irving averaging 24.0 points, 5.0 rebounds and 7.0 assists per game.

“He’s going to go down as the best player ever from New Jersey,” said Jay Gomes, the publisher of NJHoops.com and the longtime premier prep talent evaluator in the state.

“Nowadays the kids are so hyped at a young age. He was different. He wasn’t hyped. But once he arrived on the scene, he just exploded. He got real good real fast it seemed.”

As the accolades poured in and his recruitment skyrocketed — he was named a McDonald’s All-American and Mike Krzyzewski would land him at Duke — Irving didn’t get a big head, those close to him said. He appeared in the school plays at St. Patrick. He was a good student. Joe Picaro, then the school’s principal, never had any complaints from teachers about him. His best friends on the team weren’t the stars.

“He didn’t seem to ever try to make people think he was special because he played basketball,” Picaro said.

He formed a friendship with Youngblood, who is a couple of years older than Irving but routinely returned to the school, and they would have deep discussions about life, not just basketball. Youngblood was taking a philosophy course in college, which interested Irving. They would talk about Albert Einstein, college life and starting businesses later in life.

“He was always a spiritual kid,” Youngblood said.

St. Patrick meant a great deal to him. It was there he became more extroverted, Philemon said, more comfortable in his own skin. When he graduated, he told Chris Chavannes, the current coach and an assistant principal at the time, he would never forget the school, even if he made it big. Irving kept his promise. He has donated to the school, now known as The Patrick School, every year and frequently returns to hang out with members of the team.

“If it wasn’t for him, we would have a tough time existing,” Chavannes said.

Looking back, Youngblood isn’t surprised to see Irving back home. He loved the Nets growing up — his favorite player was Jason Kidd — and said it was a dream of his to play for them one day.

After officially signing his four-year, $141 million contract with Brooklyn, Irving posted a photo of himself as a child, holding an old school New Jersey Nets basketball.

Irving and Youngblood met up after Irving won an NBA title with the Cavaliers, and Youngblood recalled him saying the only way that feeling could have been topped was if it happened with his hometown team.

Now he’ll get the chance to live out that dream.

“To see him come back and actually play for the Nets, after all this time — he’s been through so much, has so much experience — it’s so exciting for everyone,” Youngblood said.