SAN JOSE, Calif. — Duncan Keith’s short pass was poorly delivered, right in Jamal Mayers’ feet. As he tried to fish the puck out from between his skates with his head down, Mayers got run over with a clean — but massive — shoulder-to-shoulder hit by a San Jose Sharks forward.

Keith, mad at the opponent and mad at himself, went ballistic, jumping the Sharks forward and trying to pound him into submission while Mayers lay flat on the ice.

That Sharks forward? Andrew Desjardins.

Almost exactly four years later (the incident was on Feb. 5, 2013), Desjardins and Keith were back at SAP Center in San Jose, only now as teammates and friends. Hockey players have long memories, though, and when Desjardins was acquired by the Hawks at the trade deadline in 2015, it was one of the first things that came up.

“It was more of a joke for us,” Desjardins said. ”It might have been different if one of us would have taken a big punch or (if Mayers) had gotten hurt, or if there was some dirtiness involved. But we just kind of laughed about it.”

As the calendar turns to February, it’s officially trade season in the NHL. The Hawks are always active this time of year, and figure to make some sort of addition by the March 1 deadline. And given the physical and fiery nature of hockey, that inevitably could lead to some awkward moments when a new face arrives.

But it happens less than it used to. Free agency, international competitions, and shared sponsors and agents have broken down the walls between opponents. Everyone seems to know everyone these days, and the bad blood that builds up on the ice rarely spills over into real life.

“You have a hatred for some guys,” defenseman Brent Seabrook said. “But there’s a lot of guys you come across through the years that you hate playing against, and then you meet them as a teammate, or at a bar, or at an All-Star game, or an Olympics, or a World Championship, or a World Cup, or whatever it may be, and you find out they’re pretty good guys.”

Even Toews gets along off the ice with his mortal hockey nemesis, San Jose’s Joe Thornton. Starting with a post-whistle punch by Thornton in 2012, the big veteran’s endless needling of Toews led to a full-blown fight on Feb. 15, 2013, at the United Center. But they were Team Canada teammates at the World Cup in Toronto last fall.

“There were a couple years there where he liked to try and push my buttons and come after me on the ice,” Toews said. “But I’ve always had a lot of respect for him.”

So while seemingly every hockey player remembers every big hit, every scrum, every cheap shot ever delivered over the course of their careers, it’s all swept aside once your enemy becomes your teammate.

There’s really no other choice.

“Once somebody becomes your teammate, you’re all in it for the same thing,” Seabrook said. “Whoever it is and whatever happened, you just have to move on.”

• This report was produced in partnership with the Chicago Sun-Times. For related coverage, chicago.suntimes.com.