This is my first time watching a series about firefighters. As someone who isn't from the United States, I recently finished binge-watching through season nine, so my perspective might differ from those who watched it when it originally aired. The initial three seasons prioritized firefighting over character relationships, which I appreciated greatly. There were episodes that genuinely moved me due to the sacrifices firefighters make for their community; "A Coffin That Small" is one example. I was drawn to Herrmann’s character and his unwavering principles, how he maintained them even in challenging circumstances, and how supportive Cindy was of him throughout those times—I missed seeing them together later on. The subsequent seasons weren't as enjoyable as the first three because they shifted the focus toward relationships (though there was still a decent balance). I didn’t connect with Gabby’s character during these seasons. While I understand Casey had his own issues, Gabby often seemed difficult to like; their relationship felt unbalanced, something that wasn’t present in those earlier seasons. She received support from Casey but sometimes didn't reciprocate it. It wasn't dislike, exactly, just a lack of connection with her character compared to the others. I did enjoy Mouch and Trudy whenever they appeared on screen. I never really understood the Kidd-Severide relationship, even as the show progressed. It seemed like Kidd’s character was developed specifically to appeal to a certain audience. That might be incorrect; it's just my impression. The three seasons that followed were well done in emphasizing relationships more than firefighting. I particularly enjoyed Brettsey during these seasons—it felt like a relationship with mutual support, and Casey appeared happy even when they experienced a separation in season nine. Otis’s death had an immediate impact for the first few episodes but seemed less significant afterward. It felt as though his character wasn't fully utilized in the seasons following his passing. I also liked Cruz and Chloe’s relationship. I stopped watching after season nine because I learned that Jesse was leaving the show. However, I did watch Brettsey through a playlist [https://www.youtube.com/watch?v=9MwfKnuIHyA&list=PLPh06C6rTjH8LwuTRjY5q46lm5L8VQgA9]. I attempted to watch season thirteen, skipping seasons ten through twelve, because it seemed like a fresh start with a new chief, paramedics, and Severide having a brother. It seems the show changed considerably after season nine, which I believe may be due to a change in showrunners, as I read somewhere.

Source on TMDB