Dahlin doesn't even turn 20 until April 13, eight days after Ehn celebrates his 24th birthday.
The two were teammates on Frölunda HC but knew each other before then from their hometown of Lidköping.
"Since we are from the same city as well back home in Sweden, I think it was natural for us to stick together," Ehn said after the team's optional morning skate at Buffalo's KeyBank Center. "We lived fairly close to each other, too. I drove him to practice for a year and a half before he got his driver's license. It's just fun, he's a really fun guy, a really nice guy so it's a lot of fun to keep in contact. Once we go play here and they come play (in Detroit), we can see other, go for dinner. It's always fun."
Said Dahlin: "Actually we grew up together in a small town with 35,000 people so I know him very well. To play with him, he was a guy that when I came up from junior who took care of me, he drove me to the rink, he gave me food, he did all that stuff. I was living on my own back then, too. So he helped me a lot. He's like a big brother to me."
Not only do the two get together when the Wings and Sabres play each other, they talk on the phone nearly every day.
Dahlin was quite young when he made the jump from Frölunda's junior team, so Ehn took him under his wing in the older brother role.
"I guess that's a little bit the relationship 'cause you have to move away from home at such a young age when you go to high schools in Sweden," Ehn said. "He was 16 when he started playing with us. Me, I had another couple close friends and tried to help him with everything so the transition went smoothly because you could see how big of a talent he is. You just want to make the transition easier for him because it is different when (some of) the guys are 15 years older than him."
It didn't take long for Ehn to see the kind of talent Dahlin possessed.
"Actually first practice," Ehn recalled. "He got a puck up on the blue line and we had a forward come pressure him and he went right-left, put it between his legs and went in and scored. That was the first time. A junior player comes up, he usually just shoots it right away, is a little bit stressed out, but just to see the patience and poise he had with the puck was unbelievable.
"Even the talk when he played juniors was you heard talk about him, like this guy is really special. Once he came along with the men's team, it was unbelievable to see. You just knew."
Dahlin expects so much out of himself that at times Ehn has had to tell him to relax a little bit.
"He wants to play so well and he wants to win so bad that sometimes you could see early on that frustration kind of got to him a little bit," Ehn said. "As you get older, you always try to tell him, it's not the end of the world. You make a mistake, there's always a next day, next day. But he really wants to win everything, he's super competitive. You have to have the balance where it's like you hate to lose but at the same time, don't let it affect you in the long run.
"I think he's done a better and better job of it because I got to know him when he was 16, and then sometimes he could, like if a game went that way, he could kind of disappear. But that's what he's worked on the most and that's why he's so good right now here."
Confidence matters a lot at the NHL level and Ehn said that's another area where Dahlin excels.
"That is what I think is so important, too, for a player with his type of style, that he is so confident, too," Ehn said. "He doesn't doubt himself for one second. I think that's one of the greatest qualities he has, that he's set on his sight and he just wants to go do it."
However, that doesn't mean Dahlin is perfect.
"He's great at forgetting things," Ehn said. "So like, packing bags, bringing stuff that he needs to bring. So that was kind of my role a little bit, making sure he had everything he needed. If we went to fly somewhere, bring his passport, that kind of stuff. He has a tendency to lose track of things."
No one who plays against Dahlin can afford to lose track of him on the ice as he is one of the rare defensemen who has been able to make an impact in the league as a teenager.
With an assist on Jan. 30 against the Montreal Canadiens, Dahlin passed Bobby Orr (72) for fourth-most points by an NHL defenseman before his 20th birthday.
The only teenage defensemen with more points are Phil Housley (132), Ray Bourque (79) and Rick Hampton (76).
Dahlin, who has 75 points (13-62-75) in his first 128 games, is a lock to pass Hampton and Bourque.
"Obviously he's a great talent," Wings coach Jeff Blashill said. "I've talked about this before, how hard it is to be a really, really great player at a super young age. If anybody can do it, a guy with his talent can. But it's a learning process, so I just think it's a league where experience matters. With that said, from our perspective he's a really good player, he's a really good talent that you have to know. He's elusive, he's good with the puck. Like any other defenseman, if you can put him under lots of pressure, you can force turnovers. So we want to make sure we're putting him under pressure and making him defend as much as we can."
It used to be a little odd for Dahlin to play against his good friend.
"Now it's 1 1/2 seasons gone, so I'm kind of used to it," Dahlin said. "Every time we play against him, we go out to dinner, we do stuff. I kind of like playing against Detroit because I can hang out with him the day before. It's always a battle on the ice, he's always trying to hit me and I always try to hit him. It's a lot of fun."
Ehn said he can't treat Dahlin any differently than he does any other opponent.
"That's my job though," Ehn said. "I can't change it whether I play him or not. I try to get in on the forecheck and make it hard for him to break the puck out. That's what I'm hoping to do tonight, too."
Dahlin missed the Sabres' 4-3 shootout loss to the Wings last week so he had a message for his friend.
"He's gotta have his head up," Dahlin said, smiling.
INJURY UPDATES: While Anthony Mantha is set to make his return against the Sabres after missing 20 games due to broken ribs and a punctured lung, others are questionable or out.
"The only one I know for sure is that (Robby) Fabbri will not play today, Blashill said. "So Fabbri's out. I'll know more on Mantha, (Frans) Nielsen and (Darren) Helm, (Madison) Bowey, all those guys tonight."
Tuesday afternoon, the Wings assigned forwards Taro Hirose and Givani Smith to the AHL's Grand Rapids Griffins and activated Mantha and Nielsen from injured reserve.
For Mantha, he has one goal in mind for the rest of the season -- staying healthy.
"That's number one on the list," Mantha said. "I want to play every game left in the season to at least get a 50-game season. Obviously it's gonna take me a couple of games to really get going I think personally. Get the legs, get the head, get the hands. Just everything combined. I'm gonna try and make it as quickly as possible but you never know. Hopefully I get enough ice time tonight and in the following the games to really get my game going and finish strong. I think last year we finished pretty strong. It could be the same mentality to try and just get some confidence, get things rolling our way a little bit more, starting now. We have what, 20-something games left? Hopefully we can manage to win a couple of those."
REMEMBERING LAST WEEK: Gustav Lindstrom made his NHL debut in Buffalo on Feb. 6 and returns to the scene less than a week later.
"It was a day I will remember forever, so it was a great day and so nice to have my parents here, too." Lindstrom said. "I will remember the feeling before the game for the rest of my life. It was a really good day."
The Wings have won two of three games since Lindstrom joined the team.
"For the most part for him, it's been for good. I think he comes as advertised - real smart, real competitive and he can pass the puck," Blashill said. "I think those three attributes are paramount for a defenseman in this league. Probably not enough guys have them. In fact, we need guys who are gonna go out there and in this chaotic game, make good decisions. Hockey is super fluid and you gotta make good decisions. He makes lots of good ones."
Mike Green, who returned to the lineup Sunday after missing six games with an injured finger, likes what he's seen from the rookie.
"I think he's great," Green said. "He's very composed. He moves the puck very well. He has a lot of the tools to create some offense, which is exciting. It's just a matter of getting some games in and feeling comfortable. I know what it was like when I was young. Sometimes it just takes a little time."