There are 21 NHL players who are former full-time captains either for their current team or, more commonly, a team they left via trade or free agency. Here are four of their journeys:

Ryan Callahan was part of a captain-for-captain trade in 2014 with Tampa Bay's Martin St. Louis. He left his home-state New York Rangers after eight seasons and became an alternate captain with the Lightning.

"You're not coming in and trying to insert yourself right away," Callahan said. "You're just there for [the captain] and, if he wants to bounce something off you, he can. But … he was named captain for a reason. You follow his lead."

John Tavares was this past summer's pre-eminent free agent signing when he departed the New York Islanders after nine seasons, five as captain. He signed with Toronto, which doesn't have a full-time captain. He, former San Jose captain Patrick Marleau and Morgan Rielly wear an 'A.'

"I don't think anyone spends too much time worrying about it or that there's a void that needs to be filled," Tavares said of the vacant captaincy. "When you are becoming a captain, it usually seems like it's a right fit or the timing's right. So I didn't try to come in and worry really about that at all. Just try to be myself."

Erik Karlsson also made big offseason news this past summer when Ottawa traded him to San Jose after nine seasons, four as captain. But gaining his new teammates' regard wasn't an issue.

"You've been around for a long time, you have certain respect. Same as I respect a lot of players in this league even though I haven't played with them," Karlsson said. "That was there when I came, and it was up to me to find my way and what I felt that I needed to do to help this team."

Joe Thornton has been the captain of two NHL franchises, three seasons with Boston before a 2005 trade to San Jose and four seasons with San Jose before the organization stripped him of the letter in 2014. But he never found being demoted to be an awkward situation.

"At some stage in your career, I think a lot of the guys in the locker room have been captains, have been assistant captains in juniors or little leagues. So they all kind of have that quality in them," Thornton said. "It's easy just to get in a room filled with good quality guys."