1x08 introduces Buttercup, a dog with cancer. Owen adopts him. They worry the cancer has come back in 2x11 but it hasn’t; Buttercup is fine. As of the end of season 4, Buttercup is still alive.
A transgender character who has transitioned mentions his experiences at various times throughout the series. At one point he is surprised with a picture of himself pre-transition, which upsets him. However, he does not explicitly mention body dysmorphia as the reason.
This episode shows multiple instances of stalking. A man stalks multiple people, showing up at a public event to threaten them. Other characters stalk him in return. A woman has been stalking a man she has a romantic obsession with and assaults multiple people in his life to get closer to him. This storyline is 3x11-3x12.
A main character describes how he drank too much after a traumatic event, which contributed to the decline of his marriage. He is shown drinking multiple times throughout the series, sometimes to excess.
In the starter scenes, a group of people at a wedding begins vomiting a lot until around 1/3 into the episode. They mention smelling it multiple times throughout the episode
A main character has PTSD as the lone survivor of his entire firehouse in an explosion a year prior to the pilot episode. It is the focus of his character throughout season 1.