In Season 3, Episode 15, "Red Rag the Bull," Mouch learns that some of his donations to a sperm bank may have produced children — some of whom are now old enough to reach out to him on their own. He chickens out of an arranged meeting with one potential child, Emmett (Joe Keery), and even lies to Trudy about having shown up.
In the next episode, "Forgive You Anything," Emmett comes to the station to tell Mouch that his actual offspring is Emmett's half-sister Lizzie Schaefer (Corinne Anderson). The episode's final scene, where Mouch finally meets Lizzie, is no doubt made more powerful by the fact that Anderson is Stolte's real-life daughter, but any chance to bring that genuine emotion back to the show is wasted as we literally never see or hear from Lizzie after their restaurant reunion.
For the rest of Season 3, Mouch is mostly relegated to the show's background, making this unnecessary two-episode wringer seem all the more senseless. The writers paint the department's father figure as nervous at the prospect of being an actual father, and then fail to deliver on what could have been a powerful and revelatory subplot. His only moments in the spotlight in Season 3 come within a storyline that could have lent some fascinating depth to his character, but instead was abandoned without explanation or having left any kind of impact on the show.
