Capitals defensemen John Carlson, left, and Karl Alzner gang up on Winnipeg’s Bryan Little in a February game at Verizon Center. The two are such good friends they’re known as “Carlzner.” (Toni L. Sandys/The Washington Post)

Consider the names. Consider how they flow together, so perfectly smooshed into one defenseman, and consider how fate made these two Capitals best friends, as if the universe would have permitted anything less.

John Carlson. Karl Alzner.

Carlzner.

“I don’t know any different,” Alzner said. “I think this is normal.”

Over the past four seasons, only four NHL defensemen have never missed a game, and two of them play for Washington. They are blue-line iron men and best friends off the ice. Dinner companions on the road. Carpoolers to the rink at home. Kindred spirits with their inside jokes. Owners of the kind of bond that factors heavily into contract negotiations, because in professional hockey this friendship is all they have ever known.

The Post Sports Live crew debates whether making the playoffs is a realistic expectation for Barry Trotz’s first season as the Capitals head coach. (Post Sports Live/The Washington Post)

They have risen through the ranks together, riding the buses in Hershey, Pa., handling the uncertainty of promotions and demotions, drafted in consecutive years as the two-headed future of Washington’s defensive corps.

“We were always together and we got along great,” Carlson said. “It just kind of forged that way, I guess.”

Several years ago, they lived in the same Courthouse apartment building, Alzner on the first floor and Carlson on the fourth, and listened to the same pump-up playlist on drives to games. They got married, with Alzner serving as a groomsman for Carlson this summer. They raised dogs — Alzner three, Carlson one plus several he has fostered. Found T-shirts that said “Carlzner” and wore them in the locker room, no matter how much their teammates poked fun.

“Oh yeah, we rip them all the time,” forward Jason Chimera said. “They try to wear it in the room, so we say some words you probably can’t say in the paper.”

“Things that don’t make us sound too good,” Alzner laughed.

Instead, Chimera can talk about how Carlson and Alzner dress in similar suits on team trips. Carlson praises Alzner’s attention to detail, and how every question he had asked — What time should we leave for the game? What time should we eat the pregame meal? — got answered. Alzner mentions how, without any brothers, Carlson offers something he imagines to be close.

“It’s just the little things,” Alzner said. “Laughing at the same things. Being able to experience milestones with games. Road trips, concerts, weddings, getting dogs. It’s like having a brother.”

The Washington Capitals and the Verizon Center are building the ice surface for hockey season. Here's a timelapse of the process. (Courtesy of Monumental Network)

Or a long-term relationship. In their early American Hockey League days, Alzner wore 47, Carlson 74. Alzner was drafted fifth overall in 2007, Carlson 27th overall in 2008. They played together on Hershey’s defense, roomed together at the hotel during camp, helped cope with the anxiety of minor league hockey.

“It’s like we’re in everyday life now,” Carlson said, “but back then when we were dealing with a lot of adversity, it was real nice to have him around. I think whenever one of us got called up, we were just so happy and we didn’t even think about ourselves and what we were thinking about. At that time . . . we both probably knew we deserved a good shot to be here full time.”

Alzner reached the NHL first, debuting with Washington on Nov. 26, 2008. Carlson followed suit the next year, against Montreal on Nov. 20, 2009. Since the 2010-11 season began, neither has missed an NHL game, 294 in total, despite some sickness last spring that caused Alzner to needle Carlson about needing to sit down.

“Just trying to tell him to take the game off,” Alzner said. “You don’t want to hurt yourself. He wasn’t too happy about that. I guess it’s just another unique thing to add.”

This season, with their consecutive games streaks intact, Carlzner will split up on the ice, pairing with different defensemen when Montreal arrives for Thursday’s regular-season opener. Alzner has skated with Matt Niskanen and Carlson with Brooks Orpik because, for all their similarities, they are still, respectively, a physical, stay-at-home defenseman and an aggressive puck mover.

But they still have the road dinners, the morning drives with music, the baseball games at Nationals Park, the T-shirts, the inside jokes. Their homes are still less than a mile apart. Their contracts don’t expire for several years, so Carlzner is safe for now.

“It’s nothing too crazy, just the same stuff most people do,” Alzner said. “But it’s blown up a little more.”