Henry Green knows there can be satisfaction in a rule. A man of nondestructive testing, he knows if a raw piece of nickel alloy doesn’t magnetize, it doesn’t contain iron ferrite. He knows if you smother the alloy with fluorescent green lipoprotein, cracks and imperfections can be revealed. Then the metal can’t be shipped to an oil rig.

He once knew that if he drove into work from his Atascocita home at 2 a.m. on Saturdays and tested metals until 1 p.m., his boss was going to be satisfied, and he could drive back to Lindsay Lyons Park in time to coach his son, Kenyon, and their youth football team. Then he could pass along the knowledge he gained while briefly playing guard for Grambling State.

Because Henry knows football players are sometimes like nickel alloys. Smother them with workouts, practices and grueling games, and imperfections can be revealed. Test them with college coursework and all the distractions of burgeoning adolescence, and even the most talented players just can’t be shipped to the NFL.

So Henry placed rules before his son — Kenyon Green, the Texas A&M guard the Texans drafted No. 15 overall — and by following those rules and others set before him, Kenyon attained his childhood aspirations in a way his father did not.

Henry grew up wanting to be like his first cousin, the late Ricky Bell, a Houston-born USC running back who finished runner-up in Heisman Trophy voting to Tony Dorsett before the Buccaneers drafted him No. 1 overall in 1977. Henry was as stout as a Coke machine in high school, but he still had some growing up to do, to which his wife, Shalonda, who graduated with him at Forest Brook High and played volleyball at UCLA, will attest.

Such a perspective can pursue compliance even when faced with the oddest rules. Take when Kenyon entered seventh grade. His height already dwarfed students several years older. The school district forced Kenyon to practice with the eighth graders, but their rules made him ineligible to play at that grade. Henry and his son did not argue.

“Hey, you’ve got to follow the rules,” Henry says. “That’s the law of the land.”

Rules help form conviction, Henry knew, and his faith supplied him a knack for explaining lessons to Kenyon in analogies. See how this sponge soaks up what’s around it? You’ve got to be careful what your mind’s soaking up. … See how those racehorses wear blinders? Don’t worry about what everybody else is doing. Henry knew his son’s receptive heart could be a gift with those who’d love him and a curse with those who’d manipulate him, and conviction could help him distinguish friend from foe.

“If you don’t stand for something, you will fall for anything,” Henry says.

Texas A&M offensive lineman Kenyon Green (55) lines up against Auburn during the second half of an NCAA college football game Nov. 6, 2021, in College Station, Texas.

Bind that all together, and you’ll arrive at a moment the Atascocita High coaching staff agrees is one of Kenyon’s most memorable and self-defining. See, the team had a rule: No cleats in the locker room. And after one practice, a teammate came clack-clacking down the hall. Kenyon stuck out an arm. Hey man, take your cleats off. The teammate protested. Man, I don’t need to take my cleats off. Kenyon insisted. Dude, it’s a rule.

Todd Moses, Atascocita’s offensive line coach, remembers hearing the commotion from across the varsity locker room. He walked through the door and saw Kenyon’s giant hand gripping the chest of the teammate’s shoulder pads and pinning him against the wall like a dart to a board.

“The guy’s trying to swing like this,” says Moses, pantomiming a desperate flail. “But Kenyon’s got him right here. He didn’t fight the guy or anything like that. It was just, ‘Man, you’re not coming in here. I don’t care who you are. That’s a rule.’”

Maybe now there’s a sense of the bigness, both of Kenyon’s size and his opportunity. The only reason he didn’t play on varsity significantly as a freshman is because he broke his right hand in the first week of preseason practice.

He was a brawny lineman who preferred playing defense. But Eagles head coach Craig Stump, a former Texas A&M quarterback and assistant coach at Tulane and Mississippi State, enlisted Henry to convince his son to play offensive tackle.

So Henry used statistics like rules.

“Son, who makes more money in the NFL other than quarterbacks?”

“Whose longevity is greater? Offensive tackle or defensive lineman?”

“What position does Coach want you to play?”

And there Kenyon was, playing left tackle as a sophomore, opposite 2021 second-round pick Sam Cosmi in a rare high school duo of eventual NFL linemen. And there, in Week 5 against North Shore, was the not-as-rare clash against an NFL-bound edge rusher: Jacksonville’s No. 20 overall pick in 2020, K’Lavon Chaisson.

The right tackle is more often the blind-side tackle in Atascocita’s offensive scheme (most teams typically shift one-on-one blocks toward left tackle), and Chaisson struggled getting around Cosmi enough in that first meeting, Stump says, that when Atascocita and North Shore met again in the 2016 Class 6A state quarterfinals inside NRG Stadium later that year, Chaisson flipped to the other side to face off against the younger Green.

“Same result,” Stump says. “You just went from one pro to the other pro.”

Notch Atascocita’s 33-27 overtime win over North Shore that night to what Moses estimates is an 8-2 overall record for the Eagles at NRG Stadium. Green reflected on those victories in his new home stadium while speaking to reporters after the Texans drafted him.

“I’ve got a good record in here,” Green said then. “So I want to keep that going. Whatever we have to do to do that, I’m ready to do that.”

Texans general manager Nick Caserio has said he envisions Green more as a guard, and if he indeed slots in at left guard, the first-round pick has the potential to bring offensive line stability to a franchise whose past pursuits of talented blockers partly led to the roster overhaul at the start of Houston’s massive rebuild a year ago.

Former head coach and general manager Bill O’Brien traded Houston’s 2020 and 2021 first-round picks to the Dolphins in an exchanged package that included left tackle Laremy Tunsil, and although the roster-wide talent gap from those missed picks persists, Tunsil remains under contract through the 2023 season.

The Texans also picked up 2019 first-round pick Tytus Howard’s fifth-year option, which keeps him under contract for two more seasons. Recently promoted coach Lovie Smith said in early May that Howard will most likely move back to right tackle if you’re “just kind of adding it all together,” which returns the 25-year-old to his most natural position.

Veteran center Justin Britt re-signed with the Texans on a two-year contract, and Caserio signed A.J. Cann, a seven-year starter in Jacksonville who could battle for the right guard spot with 2019 second-round pick Max Scharping.

Had the Texans spent their No. 3 overall pick on a pure offensive tackle, the subsequent moves considering Howard’s fifth-year option might have played out differently. But by selecting LSU cornerback Derek Stingley Jr. (who addressed another major position of need) and then trading back two spots to No. 15 and choosing Green, the Texans have strengthened an interior line that has become all the more important as NFL teams increasingly seek to pressure quarterbacks up the middle.

Of course, not every team has a seven-time All-Pro defensive tackle like Aaron Donald, whose game-clinching sack sealed victory for the Rams in Super Bowl LVI. But even in a standard football sense, the Texans’ interior line in 2021 struggled to pass-protect and pave deep enough lanes for a running game that ranked second-to-last in franchise history with 3.4 yards per carry.

Green’s dominance as a brawling blocker earned him a spot as Texas A&M’s starting right guard as a true freshman in 2019, when he faced future first-round defensive tackles in Auburn’s Derrick Brown (Panthers, No. 7 in 2020), South Carolina’s Javon Kinlaw (49ers, No. 14 in 2020) and Georgia’s Devonte Wyatt (Packers, No. 28 in 2022).

Yes, Green had been a five-star tackle, the state’s top recruit according to 247Sports. But an Aggie O-line that was in dire shape when Jimbo Fisher arrived from Florida State on a 10-year, $75 million contract needed Green most at guard.

And even after 2021 fourth-round pick Dan Moore Jr. vacated the left tackle position after the 2020 season, Green agreed to be a hybrid lineman because Texas A&M signed graduate transfer Jahmir Johnson, who’d been Tennessee’s starting left tackle. Green was named a consensus All-American while starting 12 games at four different positions, galvanizing an Aggies run game that ranked No. 15 nationally with 5.25 yards per carry.

“I’ll be shocked if he doesn’t have an unbelievable career in pro football,” Fisher said.

Green and the rest of Houston’s rookies will join the Texans’ veterans when OTA practices begin Tuesday. He’ll again be at the stadium in which he thrived at Atascocita, and he’ll be just over 30 miles away from where twin Texans flags fly outside his parents’ home.

The Greens have never been more than a two-hour’s drive from where Kenyon has played. Although LSU was Kenyon’s dream school, Henry said his son decided “Why not stay in Texas?” when the Aggies landed a championship-caliber coach in his home state.

It’s a sentiment that connected Kenyon with Smith, a Big Sandy native who appealed to his future offensive lineman during a pre-draft meeting by telling him he wanted Texas players who could help “rebuild this thing from the ground up.” As of now, 19 of the 90 players on Houston’s pre-training camp roster are from Texas.

You might almost say playing football in Texas is just another rule for Kenyon, who, when he saw the “281” area code flash on his cellphone the night of the NFL draft, thought: I’m staying home. I’m staying home.

“He’s on this great stage now,” Henry says. “Just imagine. You go out there and write this part of the novel, son. That’s amazing. You can make history. You’ve played your whole life in Texas. That’s unreal.”

Brooks Kubena, a Houston native, joined the Chronicle in 2021 to cover the Texans and the NFL after reporting on LSU football for The Advocate | Times-Picayune in Baton Rouge for three years. Kubena contributed to the AP Top 25 poll and held a Heisman Trophy vote. A graduate of the University of Texas and Clear Lake High School, he's too young to remember the Oilers but old enough to remember a parking lot was once AstroWorld.