They met at the 2016 World Cup of Hockey, when each was an assistant on Todd McLellan's staff for Team North America. But their friendship blossomed during the 2017 IIHF World Championship, when Cooper was Canada's coach and Gallant his top assistant.
They were together for more than three weeks at the tournament, played in Paris and Cologne, Germany.
"After that experience at the World Cup of Hockey] with Turk I was fortunate enough to be asked to coach Canada at the Worlds in 2017," Cooper said, "and the first guy I circled to see if he could come with me was Turk. Just because of how much respect I have for him, what he does and basically what a hell of a guy he is, just down to earth, a straight shooter."
Canada lost to Sweden in the gold-medal game, 2-1 in a shootout.
"Three weeks together, ate lunch together every day, dinner together, so you get to know a guy real well," Gallant said. "We had a lot of fun over there, enjoyed it, coached together and since that time we've been pretty good friends."
Gallant went back to the World Championship as Canada's coach last year, and Canada defeated Finland 3-2 in overtime in the gold-medal game in Riga, Latvia, on June 6.
"He won't let me forget that," Cooper said.
***[RELATED: [Complete Rangers vs. Lightning series coverage]*
Cooper won his second straight Stanley Cup championship with the Lightning on July 7.
"I've been congratulating him a lot on winning championships and when we won the World Championship last year he kept texting me," Gallant said. "It's great when you get a guy like that, a friendship."
It's about their styles as coaches, too; they're similar even though they come from different backgrounds and from opposite ends of Canada.
Gallant is from Prince Edward Island in the Maritimes. The 58-year-old played 615 NHL games from 1984-95, 563 with the Detroit Red Wings and 52 with the Lightning when they were in their infancy from 1993-95.
The Rangers are the fourth team he has coached, joining the Columbus Blue Jackets (2004-07), Florida Panthers (2014-17) and Vegas Golden Knights (2017-20).
"The thing that our team likes him about him the most is he lets you play your game," New York defenseman K'Andre Miller said. "Creative guys, he lets you do your thing. Obviously, everybody knows their role at this point of the year, but I think it's about him trusting us and us trusting him."
Cooper's relationship with his players in Tampa Bay is built on trust. The 54-year-old from British Columbia grew up with many of them as their coach in the American Hockey League before joining them in the NHL with the Lightning.
He's the longest current tenured coach with one team in the NHL (2013-22); Tampa Bay is the only team he has coached.
"He can read a room really well, one of the best I've ever been around," Lightning forward Pat Maroon said. "He gets a sense of what's the vibe in the room. Guys like to play hard for him. He's kind of a players' coach, very approachable. Guys can go into his office. That open-door policy, I think that's a huge thing as a player, especially as a young kid. If you want answers his door is always open. It makes you feel a little more comfortable coming to the rink every day."
Cooper and Gallant made each other feel comfortable doing that during the World Championship five years ago.
For the next week or so, they'll continue to try to make the other uncomfortable every time they're at the rink together.
But when the conference final is over, there will be a handshake of admiration and, more than likely, a text saying congratulations and good luck.
"Obviously, we both want to win real bad in this series," Gallant said, "but friendships are great to have around the League with people like that. He's done a great job."
Said Cooper, "I've got nothing but admiration for 'Turk.' He's a [heck] of a coach."
