8. Season 3
Season 3 kicked off in spectacular, heartbreaking fashion with the loss of Shay (Lauren German). It was one of the best episodes in the series up to that point, and it might also be why the rest of the season feels a bit underwhelming. Season 3 suffers from having to juggle lots of different subplots that doesn’t necessarily come together.
The stuff with Severide mourning Shay’s death is strong, even if his sudden decision to marry a woman in Vegas came out of left field. We’d say that season 3 works best as individual episodes, rather than a satisfying whole.