Base-Breaking Character: Farrah Mahmoud, the hospital psychiatrist. On the one hand, many see her as a Designated Villain for Kate. Other times, she's an idiot who constantly gets her own diagnoses wrong, leaving Kate to clean up the mess.
The Scrappy: Delilah, Will's one-time affair-cum-stalker. Will has an affair with the waitress Delilah, and she becomes Yandere for him. But can't fire her from his business, as it would look like he's firing her for romantic involvement. After this is brought up, she mainly just exists to cause a minor inconvenience to Will and Kate before, and is eventually fired regardless. Ironically, in a similar situation to Joanne Froggatt post-Robin Hood, her actress had more success after the show was canceled.