So when Ramirez comes back to Fenway on Friday night for the first time since the blockbuster trade that sent him to the Dodgers on July 31, 2008, it's hard to know just what type of reaction he will get. In a way, the situation is about as unpredictable as Ramirez himself.
"I don't know. He was here a long time and put up great numbers and helped win a couple of World Series," said second baseman Dustin Pedroia. "Who knows, because you never know what the fans are thinking. It should be interesting, but I don't know what to expect. It's going to be fun to see what goes on."
When he steps into the box wearing that Dodgers uniform -- with No. 99 on his back -- and is introduced by public address announcer Carl Beane, will fans think back to all the key hits he provided en route to two World Series championships? Or will they remember how disenchanted Ramirez had become by the end of his time in Boston, all but demanding the Red Sox find a new home for him in the heat of a pennant race?
"Well, you know, I might be not the right guy to comment about that, saying what the fans have to do or don't have to do," said slugger David Ortiz. "But I think people have got to keep in mind that we're talking about a guy that has a lot to do with two World Series that we won here in the first place.
"This organization has had tons of players coming through over the years. And I think as long as this organization waited to win a World Series, having a guy like Manny, especially being the MVP in the [2004 World Series], he deserves a lot of respect because of that and doing what he did, seeing things from the positive way."
Ortiz knows as well as anyone that Ramirez was downright mystifying at times with some of his antics. But he also knows the monster numbers the left fielder put up each year.
"He came in here after signing an eight-year deal and shows up very single year," Ortiz said. "It's more than earned -- respect from fans and things like that. That's the things that I would focus on as a fan."
But fans aren't always as even-keeled when they examine a situation like this.
"Once he left, I was pretty mad, because how could you do that to this great town? I am really interested to see his first plate appearance. I am pretty sure people are going to boo him," said Red Sox fan Josh Guzman. "I am bittersweet towards the situation and don't like that he left, but he helped the Red Sox get those two championships. It was sad to see him go, because he helped us a lot, so I wished he stayed here. I would personally boo him, and that is what I can imagine the fans will do as well."
Smack in his prime during his time in Boston, Ramirez hit .312 with 274 homers, 868 RBIs and posted a .999 OPS (on-base percentage plus slugging).
"He's one of the best hitters to ever play the game, so you got to watch him and learn a lot from his hitting," said first baseman Kevin Youkilis. "He had a great routine of hitting. If you sat back and watch, you got to learn a lot. He was very helpful in that respect. The one thing I learned from him was the routine of hitting and his approach."
Another thing Ramirez was through much of his time in Boston was a near constant source of entertainment. Through the good, the bad and the ugly, there was never anything dull about the right-handed hitter.
How about that night in July 2004 when Ramirez made a diving stop in short-center field of Johnny Damon's relay throw, allowing Baltimore's David Newhan an inside-the-park homer? That is a moment that will never be forgotten by anyone who witnessed it.
"That's one of the few times I was able to laugh after a tough loss," said manager Terry Francona. "I remember that night on [ESPN], they were all laughing, and it was hard not to laugh. He was so proud of himself. He left his feet and made a great play, and just listening to Damon, and everyone else, it was hard not to laugh."
How does a left fielder ever come up with the idea to cut off a throw from his center fielder?
"You know, Manny is a little bit of a different breed," said J.D. Drew. "He's got his own little characteristics and he can be one of the greatest players at times, and other times, you kind of scratch your head. He's a unique character, that's for sure."
Drew's favorite head-scratcher?
"I think a prime example of that was the time in [Anaheim in July 2008] when he dove for that ball and then rolled back on top of it," Drew said. "I don't know if he was worried about somebody shooting bullets at him or something. He was staying low on it. That's one time as an outfielder, you just kind of scratch your head and go, 'What in the world is going on in his head over there?"'
There likely won't be any comedy from Ramirez in the outfield this weekend, as Dodgers manager Joe Torre indicated the slugger will serve as the designated hitter in all three games.
But Ramirez's bat has always provided quite a storyline on its own.
Francona was with Ramirez from 2004 until the trade in '08. Francona spent much of his time marveling at what a tremendous hitter he was, but plenty of other moments putting out Ramirez fires either through the media or internally.
"A lot happened," Francona said. "[He is a] great hitter. [He] did some remarkable things on the field. Sometimes, especially early, there were times when he would make an out, and I would sit there and think, 'How did he make an out?' That's not fair. But he was so good and so dangerous, that sometimes when he made the out, you would say, 'That's not fair.' That's how good he was."
Reliever Manny Delcarmen -- who grew up in Boston as a Red Sox fan -- knows full well how much emotion the fans will have on Friday night.
"It's going to be pretty exciting with him coming back to Boston," Delcarmen said. "I want to see how the fans are going to react having him here. It will be pretty cool seeing him again. Hopefully I get to face him, so I can say in my career I actually faced him and did well."
Ramirez will arrive at Fenway with a .295 average, seven homers and 33 RBIs. At the age of 38, perhaps he is finally slowing down a little.
"He's always been one of the best hitters in the game. Having him and David back-to-back, I always thought we had one of the toughest lineups ever," said Delcarmen. "You put them in any lineup and they are going to do damage. He can go the other way or he can turn around and hit a fastball right to the Mass Pike. He did a lot for Boston and it will be fun having him back."
As was often the case during his time in Boston, Ramirez is in the midst of a season-long media boycott. When he does talk, Ramirez just about always says something that makes people laugh.
When the Red Sox were down, 3-1, in the 2007 American League Championship Series, as loose as could be Ramirez asked reporters what the big deal was.
"If it doesn't happen, so who cares? There's always next year," Ramirez said that day in the clubhouse in Cleveland. "It's not like the end of the world or something. Why should we panic?"
Ortiz still gets a chuckle out of it.
"Yeah, I remember one of the best lines from Manny was when he said it's not the end of the world," Ortiz said. "And we ended up winning that year. So that tells you that there's no way you can put pressure on the guy. He knows how to figure things out. Everybody had a way to do things and a different way to react with things. This guy, I never saw him panic. It's hard to be like that, but that's a gift. That's what makes him so good."
Last May, Ramirez was suspended 50 games for violating Major League Baseball's performance-enhancing drug policy. That was a big blow to Ramirez's image, and he hasn't been quite as outgoing as when he first arrived in Los Angeles.
"But you watch him, he still messes around when they introduce him in LA, he gets up on the top step," said Torre. "He's still having fun. When he first came over here, he was like giddy, and it sort of rubbed off on the players. And it's still been there for the players ever since then. I think the suspension last year certainly knocked him a little bit. I think he was embarrassed by it and the whole thing."
Even the Red Sox players who weren't around during Ramirez's lengthy stint with the club seem intrigued by what will be in store Friday night.
"It is going to be interesting," said center fielder Mike Cameron, who was nearly traded from the Mets to Boston for Ramirez in 2005. "I am interested to see how he is doing. It looks like he is starting to heat up. I'm looking forward to seeing him come back here. As much as the chaotic things he did here, I hope the people remember what he gave them. I am pretty sure he will get some cheers and jeers."
There were nights Ramirez simply electrified Fenway Park. Remember the rocket walk-off blast he hit off Francisco Rodriguez -- then with the Angels -- in Game 2 of the 2007 AL Division Series?
"That was a huge home run, but there are so many like that, because he's one of the best right-handed hitters to play the game," said Youkilis.
"I am excited to see him again," said Red Sox fan Heather Scott. "I liked him because he was funny and he had a great personality. It made watching the games more fun. He was my favorite, so I miss him quite a bit. I would definitely cheer him in his first at-bat. I think the reaction will be mixed. A lot of people liked him."
Through it all, Ramirez was very much a lightning rod for Red Sox Nation.
"Everyone is different," said Youkilis. "I think you question everyone at some point. It's part of the game. He's just a different guy, but there are a lot of different guys in the clubhouse. As a superstar, you stand out a little bit more."
Whatever Ramirez does during his three-day visit back to Boston, it is sure to stand out.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.