The Character Everyone Forgets Stranger Things' Joe Keery Played In Chicago Fire

When we first met Steve Harrington (Joe Keery) in Season 1 of Netflix's nostalgic sci-fi mystery series "Stranger Things," he was really only a minor character — and an antagonistic one at that. He first appeared as a typical high school jock who bullied Jonathan Byers (Charlie Heaton) and was a love interest to Nancy Wheeler (Natalia Dyer).

Yet, as the series went on, Steve turned a corner, becoming one of the most beloved characters on the show and playing a significant role in Seasons 2 and 3. He went from being a cocky bully to the kind-hearted comic relief of the Hawkins team as they fight against the supernatural.

This is due in no small part to the spectacular performance of Keery, who made Steve's transition from small-town jock to lovable goof believable. While Steve Harrington is far and away Keery's most recognizable role, fans might be surprised to learn that before he ever set foot in Hawkins, Indiana, he had a small part in NBC's "One Chicago" franchise.

In Season 3, Episodes 16 and 17 of "Chicago Fire," Joe Keery appears as a character named Emmett — introduced as the biological son of firefighter Randy "Mouch" McHolland (Christian Stolte). When Mouch learns that a security glitch has compromised his identity as a former sperm donor, he receives a voicemail from Emmett shortly after — claiming to be his son and asking to meet his biological father.

Mouch deletes the message out of fear and tries to ignore the whole situation until Emmett tracks him down and reveals that he is not his son but has been trying to reach Mouch on behalf of his half-sister Lizzie –- Mouch's true biological daughter. It's a dramatic twist that's integral to the development of Mouch's character, who ends up revisiting Emmett and finally reuniting with his daughter.

He only appears in two episodes, but Keery manages to leave a lasting impact on the series with the reveal about Mouch's daughter, and it's interesting to look back on how drastically different his work was before becoming the iconic Steve Harrington.