The right-handed Richardson, 23, is the first pitcher to allow a home run on each of the first two pitches of his major league career in the Elias Sports Bureau's pitch count era, which dates back to 1999.
Abrams and Thomas teamed up to hit two fastballs a combined 808 feet. Abrams reached the first section of seats down the right field line with a 402-foot shot for his first career leadoff homer. Thomas followed with a 408-foot drive to center field for his third homer of the series.
"As the leadoff hitter, I'm looking fastball," Abrams said. "I got one middle up and put a good swing on it."
"It was cool to put another good swing behind him," Thomas added.
"We got off to a great start," Washington manager Dave Martinez said. "Two pitches, two runs. Those two are catalysts for us. They've been consistent in getting us going. They've been doing well for us all year. CJ and Lane are doing the job for us."
Abrams finished with four hits and Thomas went 7-for-13 with eight RBIs in the series.
Richardson went 3-0 on Joey Meneses, the next batter, before throwing a strike that sparked a sarcastic cheer from the crowd.
He rebounded from his rocky start to add two hitless innings, finishing with 4 hits and 4 runs with 3 walks and 2 strikeouts.
"I didn't think I made that bad of a pitch," Richardson said. "I might have missed a little bit more middle than I wanted to. I think he was just ready for a heater and hit it.
"I don't think I'd redo it. I was just thinking that I had to get myself dialed in and get a few outs here. There is always nerves but I do a pretty good job of managing it. It wasn't necessarily the nerves that got the pitches hit. It was me."
"It was an unfortunate way to start the game and major league career," Reds manager David Bell said. "He has a long one ahead of him and just the way he was able to keep pitching and hold it together for three innings, really says a lot about him. It is a tough way to start, I mean, you get off to a rough start like that in your debut. We've seen guys back away. We've known that about Lyon. He was given an opportunity there to demonstrate who he is and why he's going to be so good."
The Associated Press contributed to this report.