Philadelphia Phillies' Bryce Harper watches a video tribute from the dugout before a baseball game against the Washington Nationals at Nationals Park.

WASHINGTON — The first boos, guttural and loud in a mostly empty ballpark, greeted Bryce Harper during pregame introductions 15 minutes before the rain-delayed first pitch Tuesday night, as he stood in the Nationals Park visitor’s dugout wearing another team’s uniform.

Jeers again filled the chilly air when Harper walked to the plate in the first inning for his initial at-bat as a Nationals opponent. More came while he awaited each pitch from Washington’s Max Scherzer, negativity interrupted only by the sheer-joy roars after each strike of his eventual whiff, which concluded with a swing-and-miss at an 85 mph changeup.

A similar scenario — boos before each pitch, cheers after each strike — played out in the third, when Harper struck out again, this time on a 92 mph cutter he couldn’t touch. He got a better result in the fifth, doubling to right off Scherzer, then standing on second base and waving toward the dugout in one of the Phillies’ many choreographed celebrations.

In the bottom half of the first inning, there was booing as Harper headed out to play right field — where fans in the front row of the bleachers wore shirts that spelled out “T-R-A-I-T-O-R” — and when he caught Adam Eaton’s fly for the first out.

Harper had said he expected a mixed reaction from spectators reacting to his departure via free agency to sign a $330 million, 13-year deal with the Phillies.

Sure sounded rather one-sided.

Hours earlier, Harper described his arrival for his return as “definitely different” but also “normal.”