TORONTO – How deep is their love?

Put it this way: One man asks Matthew Tkachuk Monday which Toronto Maple Leafs rookie he feels closer with, Mitch Marner or Auston Matthews, and the Calgary Flames’ freshman can’t pick between besties. Or, at least, he’s smart enough not to hurt one friend’s feelings on national television.

“That’s a tough question. I’m pretty good buddies with each,” Tkachuk said.

Having served as a wingman for the two Leafs he’s joined in the Calder Trophy hunt, it was natural for Tkachuk to speak with Marner on the phone and hang out at Matthews’ apartment last night, in advance of Monday’s game.

“Probably Mitch is a little louder. They’re both fun guys to be around, both good buddies I’ve had. It’s fun seeing them again. Great memories.”

Three 19-year-olds linked by a shared passion, an identical pursuit, and a Snapchat feed full of memorable on-ice moments. Since the Flames’ NHL-ready sixth-overall pick returned from a cut hand on Nov. 15, Matthews (26), Marner (25) and Tkachuk (24) rank one, two and three in rookie scoring (thanks, in part, perhaps, to Patrik Laine’s concussion).

Born in Scottsdale but groomed in St. Louis, Tkachuk first faced off against Matthews in peewee. The future No. 1 pick was representing the Arizona Bobcats at the time.

“Their whole team was terrible except for him,” Tkachuck said.

Their bond would form years later, through the U.S. National Development Team Program, and would strengthen through success.

“When we were trying out for our U.S. team, nobody heard of him,” Tkachuk recalled. “He came out of nowhere and had about 15 goals in that tryout camp.”

Since sharing an under-18 gold medal with their country, Matthews and Tkachuk have remained close.

“We had a slogan with USA: Champions walk together forever. I still keep contact with all those guys,” Tkachuk said. “What we had was special.”

He reminisced about a USHL game in Wisconsin.

“We were up by three or four goals at the end of the game and everybody’s packed it in on the bench. Auston picks it up behind the net and goes through every single player on their team and our team and scores,” Tkachuk said.

“Guarantee you, he has that video on his phone. I remember him sending it to me a bunch of times back then to show how good he was.”

Tkachuk and Marner’s friendship also stems from success, as they lifted the Memorial Cup together as London Knights last spring. They’ve maintained a group chat with linemate and Coyotes prospect Christian Dvorak all season, just “to shoot the crap about stuff,” Marner says.

Describing Tkachuk, Marner uses phrases like sneaky, in your face and under your skin. How his former teammate approached a blowout over the Mississauga Steelheads stands out, in particular.

“We were up 6-something and he was still getting in people’s faces and drawing penalties. I think he drew a five-minute penalty, then next shift he drew another two minutes. That’s the kind of guy he is,” Marner said.

“People just don’t like the feeling of him always around them. That’s what he’s good at.”

Tkachuk has a Marner story, too.

“We had a line brawl against Sarnia,” Tkachuk said, with a smirk on his face. “The ref had their biggest defenceman, and Mitch is obviously not as big as the refs. I remember him jumping up and punching over top of the refs. I thought that was funny. It’s on YouTube.”

Yep:

Matthews describes Tkachuk as a laid-back cracker of jokes, but one who flips to dead serious at puck drop and morphs into “one of the smartest hockey players I’ve ever played with.”

One of the most annoying, too. In addition to chirping, Tkachuck commits as many penalties as he draws; his 90 PIMs are far and away the Flames’ most.

That doesn’t shock Matthews.

“He always led the national team in penalty minutes, and I think he led his team in London. He’s not afraid to stand up for himself either,” Matthews said. “You definitely gotta watch out for him.”

Like the time Tkachuk snatched San Jose star Brent Burns’ stick mid-game and took it to the Flames bench. “It’s almost like stealing a guy’s girlfriend,” Flames coach Glen Gulutzan compared. Tkachuk, Matthews reveals, then asked Burns post-game if he could keep it for real (but no luck).

Matthews on the Burns’ incident: “That’s the type of stuff he likes to do.”

Marner on the stick-theft: “That’s the kind of guy he is. Maybe not steal it into a bench, but I’ve seen him steal sticks out of guys’ hands a couple times last year.”

Prior to 2016-17 — the year of the Canadian team rookie — Marner and Matthews didn’t have a shared history. Tkachuk served as their Kevin Bacon, their one degree of separation. Now that Tkachuk’s mutual friends are wearing matching fedoras and singing the same Bon Jovi anthems, the buddy love triangle is complete.

“They’re both going through the same thing, both rookies on their team, both high-end players who had a lot of pressure on them coming up, and they’re in a similar spotlight in Toronto,” Tkachuk said.

“If they weren’t friends, something would be wrong.”