What will the crowd's reaction be the first time he steps to that plate in a uniform other than Washington's? What sort of tribute will there be from the Nationals? What sort of gesture will the outfielder himself make?
And how will Harper, who loves the spotlight, fare in the reunion — especially against Max Scherzer? "I'll always remember and cherish all the screaming and yelling and the exciting times that we had the last seven years. Like I've said before, I wish them nothing but the best, all the players in that clubhouse. It's a great fan base. Great city to live in," said Harper, who announced Monday on social media that his wife is expecting the couple's first baby. "Excited to go back. And excited to compete."
He is off to a good start in his new home, helping the Phillies go 3-0 — they are the only unbeaten team in the majors — with a pair of homers against the Atlanta Braves, each marked by elaborately choreographed celebrations with teammates.
The Nationals, meanwhile, are 1-2 with some serious bullpen issues after avoiding a sweep against the New York Mets thanks to a ninth-inning homer Sunday by Trea Turner. There has been something of a parlor game in both the nation's capital and Philadelphia lately, trying to guess how Harper will be greeted upon his return.
He did, after all, win 2012 NL Rookie of the Year and 2015 NL MVP honors with Washington. He helped the club make four playoff appearances. He thrilled spectators by winning last year's All-Star Home Run Derby in his home ballpark.
But he also left as a free agent to join a division rival. "I love all human psychology," Phillies manager Gabe Kapler said. "I love to see how people respond to moments like that — the players, the fans and the cities."
Harper said he expects "some cheers, some boos, as well." Thousands of Phillies fans are expected to make the trek down Interstate 95. "Bring it on, if that's the case," said Nationals lefty reliever Matt Grace, who said he has thought about what it might be like to pitch to his ex-teammate.
"Treat it just like any other situation: Go after him," Grace said. "Not going to treat it like anything else. I'm sure he'll do the same." Scherzer (0-1, 2.35 ERA) will make his second start in Washington's first four games of 2019.
The three-time Cy Young Award winner said it will be "weird" to see Harper in a No. 3 Phillies jersey instead of his old No. 34 Nationals uniform. "He's signed there forever, basically. At least 'forever' in my career. We're going to be facing each other a lot; this is just the first," Scherzer said. "So whatever happens on Tuesday, it's going to be the course of a career facing him. This is just Round 1."
AP Sports Writers Dan Gelston in Philadelphia and David Ginsburg in Washington contributed to this report.
More AP baseball: https://apnews.com/MLB and https://twitter.com/AP_Sports