Eight years ago, Washington Capitals defensemen John Carlson and Karl Alzner would drive home from games together and laugh. Then one of the youngest defensive pairings in the NHL, Carlson and Alzner would go back and forth about “how cool the game was” that night, the big play that changed it or something memorable one of their more famous teammates did.

Their careers mostly ahead of them, they were “just living the dream,” they always joked.

Alzner left the Capitals as a free agent in 2017, and Carlson is no longer the young, relaxed, talented defenseman playing a supporting role. At 29 and already in his 11th NHL season, Carlson is an alternate captain mentoring a new crop of young defensemen, and he has blossomed into a star himself.

In October, he set a franchise record for points in a month by a defenseman with 23 (seven goals and 16 assists), and he was named the NHL’s first star of the month. He finished two points shy of the league record for a defenseman in October, set by Calgary’s Al MacInnis in 1990.

“Just seeing the transformation from always being a good defenseman to being a top-five defenseman in the league, it is cool to see it all pay off because it’s been a journey,” Alzner said. “But it’s been a fun journey, I think, too.”

Being named one of the Capitals’ alternate captains at the start of this season was a crucial step in Carlson’s growth. He was given the “A” previously worn by Brooks Orpik, who had retired. After years of learning from older defensemen who rolled through Washington, including Orpik, Matt Niskanen and Mike Green, Carlson is now securely at the helm.

“The biggest change for me is just growing up,” he said.

As a newly minted leader, Carlson admitted, he can’t be as laid-back as he was when he was younger. The past five years, those in the veteran defensive corps never felt a need to police one another; they all knew their roles and followed them accordingly. Now, a less experienced group looks to Carlson to set the standard, but don’t expect him to alter what got him there in the first place.

“I could be in the background, and now I can’t be in the background, if that makes any sense,” Carlson said before the season. “I’m not going to change who I am. I’m not going to be a drill sergeant now and stand at attention all the time, because that would be taking away from my game and, you know, who I am is how I play the game. I think that’s one of my assets.”

Carlson has pushed himself to help the progress of younger defenseman, including Jonas Siegenthaler, with whom he was paired to start the season. Capitals Coach Todd Reirden said he believes Carlson knows that with his experience and contract — he signed his eight-year, $64 million deal in the summer of 2018 — he needs to bring along younger players for the team to make another Stanley Cup run. That, Reirden said, is the “true understanding of a leader.”

“It was easy to maybe be a little more jokey and loose in certain situations because we had Brooks and Nisky. … And now that they’re gone, I’m not going to be a different person,” Carlson said. “I’m not going to be, you know, nitpicking everything and the hard-ass. I’m not going to be one of those guys ever.”

Carlson’s attitude has been apparent from the beginning of his tenure with the Capitals. Alzner described it as an asset to elite defensemen, who tend to benefit from “going with the flow” and pushing forward as the game constantly changes.

It is also the type of personality that can catch some players off-guard. Alzner didn’t believe the then-19-year-old could be as young as he was when he came to the Capitals. Carlson could blend into any group, young or old. And his play on the ice was on par with that of the veterans.

Carlson is now one of the longest-tenured players on the team, and he has two sons: 4-year-old Lucca and 1-year-old Rudy. Starting a family and having the chance to bring his kids to the rink had long been a dream. During multiple television interviews, Carlson made sure to close with a simple, “Hi, Lucca!”

“I remember Mike Knuble had the oldest kids when I was young, and just seeing them around the rink, you know, me personally, you think of it as a young guy,” Carlson said. “You’re like, ‘Oh, wow, that would be cool.’ That was me.”

Carlson’s softer side comes out when he talks about his kids — his face lights up with every question. The same goes for when he starts talking about Alzner and other former teammates.

“Once he is in your corner, he’s willing to bend over backwards to help you with stuff and be there for you,” Alzner said.

Reirden saw that type of commitment six years ago, when he joined the Capitals as an assistant coach. Reirden said over the years they’ve worked together to send a message of how he wants to be viewed.

Carlson has knocked down every task Reirden has put in front of him, with one big hole left on the checklist: winning the Norris Trophy as the NHL’s top defenseman. To get Carlson prepared for this moment, Reirden nudged him to study leaders in other sports, such as Tom Brady and Stephen Curry.

“To cultivate leadership, it doesn’t just happen by accident,” Reirden said.

Last season, Carlson tallied 13 goals and 57 assists, with a career-high 25:04 average ice time. During the team’s championship run in 2018, he had five goals and 15 assists after a regular season in which he recorded 15 goals and 53 assists, averaging 24:47 of ice time. He led all NHL defenders with points (68), and his goals were tied for eighth. He has been in the Norris discussion over the past two years, finishing in the top five in voting both years but never among the top three.

But now that Carlson has started to rack up points, he doesn’t want to be pigeonholed as an offensive defenseman.

“I just think it’s funny when people have these preconceived notions about certain people and, you know, like, ‘I’m an offensive defenseman,’ but I’ve played on the first penalty-killing unit for 10 years now,” Carlson said. “That’s not really how it works if you’re an offensive defenseman, right?”

In a Capitals dressing room filled with stars, Carlson sometimes gets overlooked. When asked just how much Carlson’s play has been underrated, Nicklas Backstrom immediately cut in quickly with “A lot.”

“He’s one of the best defensemen in the world,” Backstrom said. “And me personally, I love the guy. I love the way he plays. He plays both ways. He’s our best defenseman every night.”

With all the points Carlson has racked up to start the season, the national media is paying more attention. Alex Ovechkin is normally the center of attention, but last week in Toronto, Carlson drew the most media members. Almost every day on a five-game road trip, he stood in front of his dressing room stall and answered the same questions over and over about his record start.

For Carlson, it was another step forward, out of the shadows and toward center stage. As for the Norris Trophy conversation, Carlson refuses to promote himself and keeps his focus on leading his teammates as the Capitals’ top defenseman.

“I would love to win or be nominated, whatever they call it, but I don’t want to lose sleep over not,” Carlson said. “As long as, you know, my teammates come up to me and say, ‘Hey, I think you deserve this or that,’ that means more than actually it would mean to win it.”