The Rangers acquired Vatrano, a forward, from the Florida Panthers for a fourth-round pick in the 2022 NHL Draft on Wednesday.
He made his New York debut in a 2-1 loss against the New York Islanders at Madison Square Garden on Thursday, skating 14:47 on a line with Artemi Panarin and Ryan Strome.
Meanwhile, Trouba was mum on how he found the picture after all these years, saying only that someone sent it to him.
"I'm not going to say anything because there might be more out there," Trouba said.
"I think if you dig deep enough you can find four or five of those [pictures], Vatrano said. "Keep digging. Go ahead."
In this one, Trouba, with short blonde hair and a big old smile on his face, is sitting behind Vatrano, who took the selfie and tweeted the picture on Nov. 4, 2011.
Vatrano has headphones on, a closed-mouth grin and wrote in the Twitter caption, "Little silent reading with @JacobTrouba."
They were teammates at the time in the United States National Team Development Program.
Vatrano was also teammates with defenseman Adam Fox and forward Chris Kreider on the United States' team in the 2016 IIHF World Championship. Fox was his roommate during the tournament in Russia.
"Trying to make him feel as comfortable as he can," Trouba said.
