The first half of Chicago Fire and Chicago P.D.'s two-night crossover event kicked off with a bang, with a much-anticipated Brettonio reunion that didn't exactly go smoothly.

After arriving at Firehouse 51 in a huff, Antonio unexpectedly ran into Brett (Kara Killmer), who was headed inside for the start of her shift. Immediately changing his attitude, the Intelligence detective greeted her in what turned out to be their first face-to-face since breaking up on Fire earlier this season. The last time they were in the same room together, Antonio had planned a nice home-cooked dinner for Brett. Unfortunately for him, Brett decided to end their relationship after a harsh encounter with his ex-wife made her realize they weren't ready for things to get so serious. So there were some feelings to sort out.

The surprise reunion, while uncomfortable for the exes, did elicit a charming one-liner from Brett, who acknowledged the weirdness of their situation.

"Well, I for one, am very glad that we can be together and it's not awkward," she told him during the encounter.

"That was a great line from Brett to basically calm things at the moment and make light of it," Jon Seda explained to TV Guide. "It's awkward for Antonio. He made her a great dinner. She walked out on him. Who does that?" added Seda.

The reunion also came at the most inopportune time for the Intelligence detective, who only headed to the firehouse to search for his daughter and scold her about her online activities.

"It's right smack in the middle of [when] he's going to find his daughter and get into it with her [about] this whole social media thing and boom! There's Brett," Seda said. "Brett brings out a whole 'nother side of Antonio that you don't usually see so I think that moment was kind of awkward but when she makes light of it, that kind of settles things."

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Despite the awkward moment, Seda teased that the former lovebirds may get another shot at a reunion — which we hope goes a lot better — in the near future. "I think someplace in Chicago Fire's side of this crossover, you might not see the last of them," he said.

The two-night crossover event concludes with Chicago Fire on Thursday, March 8 at 10/9c on NBC. Meanwhile, you can catch Chicago Med on Tuesdays at 10/9c and Chicago P.D. on Wednesdays at 10/9c.

Kara Killmer, Jon Seda; Chicago FireKara Killmer, Jon Seda; Chicago Fire