"No, you don't want to poke the bear," Marchand said.
Chara faces the Bruins on Saturday for the first time since leaving Boston as a free agent, signing with the Washington Capitals in the offseason. The Bruins wanted to decrease his playing time in favor of giving younger defensemen a longer look.
Chara, 43, felt he could still be a regular contributor in the NHL, and his 14-year tenure with Boston ended with a one-year contract in D.C.
"I love them as my brothers," Chara said on Friday. "We understand this is a business. We have to play for our teams and compete out there. But at the same time, we have something that is very deep, goes far back and we'll cherish those memories."
Marchand knows whatever adoration is shared between the Bruins and Chara won't transfer to the ice.
"He's the kind of guy where when he's out there, you're an opponent. He's not going to have any friends out there. He's going to play the game and compete and battle," Marchand said. "I'm not going to poke the bear in any way. The biggest thing I can do is just skate away from him. If you get within that reach or his grasp, then you're not going anywhere."
Chara said he doesn't expect anything out of the ordinary from Marchand in their first meeting, either.
"I don't think it's going to be any different," he said. "He's a guy who will always go out there and compete for his teams. I think we had many practices against each other and we both compete pretty hard. I don't expect anything else from him or anybody else."
Chara has averaged 20:29 in ice time per game for Washington. In eight games, he has a goal and two assists, scoring his first as a Capital in their win over the New York Islanders on Thursday. When asked if he's proven he can still be a regular player rather than the spare part the Bruins saw him as being, Chara said: "I'm just trying to focus on trying to help this team as best I can."
There's more to Saturday's game (7 p.m. ET, ESPN+) than this emotional reunion: The Capitals are in first place in the East Division with 13 points in eight games, and Boston is right behind them with 11 points in seven games.
"I don't think it's going to be that much about me playing against the Boston Bruins. I think these are two really good teams, playing for two points that are going to be out there tomorrow to grab," Chara said.
Still, it's Zdeno Chara vs. the Boston Bruins. The former captain. The defensive star. The man who first hoisted the Stanley Cup when Boston won for the first time in 39 years back in 2011.
"It'll be weird seeing him in a different uniform," Marchand said.