Contains spoilers for “Chicago Fire” Season 13, Episode 19 — “Permanent Damage”

Fans have been wondering what sort of connection Natalie (Ava Torres) might have to Stella Kidd (Miranda Rae Mayo) after Natalie surfaced during Episode 17, “A Beast Like This.” A standout in Stella’s Girls on Fire program, Natalie seemed to know way too much about her teacher. When Stella figures out that Natalie is a child she saved at a fire 10 years before, the stakes go up. Why is Natalie so invested in Stella? Might she see her mentor as the only safe adult in her life and be angling to be adopted by Stella and Kelly Severide (Taylor Kinney)? Or could something more sinister be afoot?

Viewers get more answers during “Permanent Damage,” but they prove a bit disappointing. When Kelly looks into the house fire, Natalie explains that she’s approached Stella because she wants her rescuer to reopen the case, claiming she has evidence that her sister intentionally started the blaze. But Kelly’s investigation shows a routine electrical conflagration with no sign of foul play. When he tells Natalie this, she shoves what looks like a leather-bound diary at him and says Stella knows what it is. While the show’s trying very hard to stay cagey about Natalie’s life and past, the way “Chicago Fire” handles this reveal is a letdown.

If the fire was such a big deal, Stella’s muted reaction to remembering it makes no sense. When Stella Googles Natalie in “A Beast Like This,” she behaves as if Natalie is just another girl she rescued, not a part of her tragic backstory. Unless that diary means something, it’s the last fire she fought before transferring to 51 and nothing more. But Natalie’s intense interest in firefighting, her drug use, and her secretive behavior about where she lives demands a much more compelling storyline.