Chicago Fire knows what it's doing. The show has been on the air for 13 seasons, and has become one of the premiere procedural dramas on any network. The cast is top notch, the crossovers have gotten increasingly better with time, and the writers have an excellent grasp on their characters.
The writers have had another fun trick up their sleeve, however. They have been implementing a cool bit of business dating back to the second episode, but it's been so subtle that few fans have noticed. It's all about the titles. The title of each episode derives from a line of dialogue in said episode. We stumbled upon this very practice thanks to the Wolf Entertainment Instagram page.
Chicago Fire uses dialogue as episode titles
It's unclear whether the title or the dialogue comes first, but it is clear that the writers have taken extra care to make sure that the phrase or word that defines a given episode makes its way into the story as a piece of dialogue. Wolf Entertainment even provided examples of this practice from the current season.
We got to see Mouch (Christian Stolte) use the phrase "born of fire" in the namesake episode, the same way we saw Chief Dom Pascal deliver the goods during a crucial moment in the One Chicago crossover "Into the Trenches." Even supporting characters like Harold Capp (Randy Flagler) have had the change to drop the title in an episode like "A Monster In the Field."
The one exception to the episode title/dialogue role is the pilot episode. It's hard to organically work the word "pilot" into a pilot episode without drawing attention to itself, so we can understand why the practice started with season 1 episode 2.
Chicago PD follows suit with this practice
The same practice has been implemented on Chicago PD, which was the first Chicago Fire spinoff to air on NBC. Once again, the procedural drama started dropping episode titles in episode two, and has done so ever since. Chicago Med is the lone outlier in this regard. The medical drama doesn't make a point of incorporating episode titles into the dialogue.
Instead, Med employed a different trick. We use the past tense here, because it no longer does. For the first six seasons, the show made a point of matching the amount of words in a title to the number season it was. Season 1 featured episode titles with one word, season 2 with two words, and so on. It was another clever idea, but it would've been hard to keep going into double digit seasons.
That said, Fire and PD are still employing their dialogue practice, so keep an ear out next time you watch an episode!