SOUTH BEND — For ex-Duke defensive end RJ Oben, walking off the field at Wallace Wade Stadium after a last-minute defeat against Notre Dame football was almost too much to process.

Certainly, that was the case in the raw moments that initially followed the 21-14 thriller on the final Saturday night in September, and it became ever stranger to ponder after the offseason developments that landed Oben and Riley Leonard, the losing quarterback that night, on the Irish roster as high-profile transfers.

“It’s surreal, honestly,” Oben said recently. “During the season, playing that game, I didn’t think of being on the other sideline, being in those colors.”

Not after watching Leonard hobble off on crutches as a result of Howard Cross III’s game-clinching strip sack.

“It’s hard when the quarterback, the centerpiece of that offense, of that team, goes down,” Oben said.

And now? Still learning their way around the Notre Dame football facilities, Oben and Leonard keep stumbling upon reminders of that pivotal night in Durham, N.C.

“I see (video) clips around the building of our game against Notre Dame,” Oben said.

He paused, caught himself and smiled.

“Going against Notre Dame when I was at Duke,” he added. “It’s crazy to think, when you look back.”

This whole us-and-them conversion might take some time.

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At 6-foot-3 and 263 pounds, Oben already was squarely on Notre Dame’s radar in early December when Joe Alt helped put him over the top.

For 60 grueling minutes, Oben and the rest of the Blue Devils’ talented defensive front, including former Irish defensive tackle Jamion Franklin, had given Notre Dame’s All-America left tackle all he could handle.

Riding in the car with Alt after the Lombardi Award ceremony in Houston, Freeman and the projected top-10 overall NFL draft pick started talking about transfers.

“Who are you guys recruiting?” Alt asked.

“We’re going after the kid from Duke that just got in the portal,” Freeman recalled saying as he told the story on early signing day.

Alt clearly remembered Oben, a fierce pass rusher who shared with him an NFL lineage. Roman Oben Sr., who played his college ball at Louisville, spent 12 years (1996-2007) in the NFL as a left tackle with four teams.

A third-round draft pick of the New York Giants, Oben spent his first four years lining up next to a tight end named Howard Cross. Now their sons are Notre Dame teammates.

The elder Oben, now the NFL’s vice president of football development, brought along a fairly talented son of his own. RJ Oben didn’t start playing tackle football until the seventh grade, but the late-blooming product of St. Peter’s Prep in Jersey City, N.J., seems to be making up for lost time.

“He was probably the best one I went against,” Alt told his coach.

“I was like, ‘I’m good,’“ Freeman recalled. “Joe Alt saying that, I’m good. That confirms what I saw on film. … We were looking for a defensive end, and we couldn’t find a better one.”

Oben, who has 13.5 sacks over the past three seasons, was shut out in the sack department against the Irish, but he played 31 snaps that night and was credited with a pair of quarterback pressures. As Hartman waited to pay his respects to Leonard afterward, Oben and Alt exchanged the salute of warriors.

“After the game I talked to him a good amount,” Oben said. “We game-planned for each other, right? I wish he would have stayed so we could have had some of those battles in practice.”

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Word got back to Oben about Alt giving him a full endorsement when Freeman raised the idea.

“I’m glad he said those things,” said Oben, who has started 32 of his 50 career games over the past five seasons. “He was definitely a great player, someone I really respected and truly loved going against.”

The same, Oben said, held true for former Irish right tackle Blake Fisher, who joined Alt in turning pro after just three seasons at Notre Dame.

“Blake obviously was a great player as well,” Oben said. “Loved going against those guys.”

Trust factor is high for RJ Oben and fellow Duke transfer Riley Leonard

While Leonard won’t have the benefit of those bookend tackles this fall, he will have the privilege of playing one last season with Oben as his teammate.

Even as Leonard’s junior season spiraled into injury oblivion before season-ending toe surgery, Oben saw the same leadership traits that made the dual-threat quarterback a must-get for Notre Dame.

“Riley was great,” Oben said. “What spoke the most about Riley’s resilience and his leadership was the fact his presence on the team was still just as felt. He’d still come in for every workout. Every practice, his voice was still there. We still believed in him, and everything (revolved) around him still, even with the fact he wasn’t playing.”

Coming off a mid-January TightRope procedure on his right ankle, Leonard was confident he’d be ready for spring practice when it opens on March 7. Oben sounded just as eager to see his friend and fellow Duke transfer take command of their new surroundings.

“The fact he’s able to bring people together around him and lead by example and be someone that the guys can look up to is something that I’ve always (admired) about Riley,” Oben said. “I love his hard work. I’m glad he’s here.”

Oben announced his transfer commitment on Dec. 13, one day after Leonard went public with his.

“I guess I knew a little earlier than everyone else that he was coming here,” Oben said with a smile. “Obviously, knowing what the situation was and what the team was going to look like plays into it. We obviously had our different reasons for entering the portal, and what our opportunities would be were different in that sense.”

And yet, there was no denying the attraction of this particular combo, one that walked off the field last September in defeat but now hopes to lead Notre Dame to the newly expanded 12-team College Football Playoff.

“Having someone that I played with and someone I have trust with coming up to build something else on a new team was definitely something I appreciated,” Oben said. “Having talked with him about what he liked about this place drew me into coming here even more.”

And whenever Cross makes good on Leonard’s public request for a fancy steak dinner, well, Oben wouldn’t mind tagging along then, too.

Mike Berardino covers Notre Dame football for NDInsider.com and is on social media @MikeBerardino.

This article originally appeared on South Bend Tribune: Joining Notre Dame football proves surreal for Duke transfer RJ Oben