Romano had shut out the Pirates for eight innings Saturday.
"I plan on being teammates with Sal for a long time," Stephenson said with a smile.
"[Stephenson] fits in, no question," Reds catcher Tucker Barnhart said.
Stephenson (5-5, 5.01) had faltered Tuesday in St. Louis, a 13-4 loss during which he was charged with six runs (four earned) over three innings. That forgettable outing, however, followed four consecutive strong starts (4-0, 2.38), including a 9-5 Reds victory Aug. 25 over the Pirates, when Stephenson struck out the first six batters he faced and 11 over 5 2/3 innings.
He was nearly as effective Sunday, when the only hit Stephenson surrendered over six innings was to Pittsburgh's Gerrit Cole, the opposing pitcher. Cole's third-inning double to left-center followed a leadoff walk and gave the Pirates their best scoring opportunity against Stephenson. He recovered nicely, however, striking out John Jaso and getting Jordan Luplow and Andrew McCutchen to pop up and leave baserunners stranded at second and third.
"After the first couple innings, I made adjustments and got settled in," Stephenson said.
After Cole's double, in fact, Stephenson retired 11 of the last 12 batters he faced. When Stephenson's spot in the batting order came up in the bottom of the sixth, Jose Peraza pinch-hit and Stephenson called it a day.
"The first three innings, he was all over the place; he was not sharp," Reds manager Bryan Price said. "All of a sudden, in the fourth, fifth and sixth, here he comes. That's what you want to see."
The 24-year-old right-hander began the season in the Reds bullpen, but was sent down May 30 with an 8.03 ERA after 13 relief appearances. He was recalled July 22 and has been used primarily as a starter since.
"He started using a slider in Spring Training for the first time that is now a really good pitch for him," Barnhart said. "His fastball and curve have continued to develop.
"We have a lot of young pitchers putting their best foot forward around here. It's fun to be a part of."
Andy Call is a contributor to MLB.com based in Cincinnati and covered the Reds on Sunday.