10 Small Details You Only Notice Rewatching Dexter
6. Easy As Pie
In season three, episode seven Dexter is finding himself conflicted when he is considering killing someone who Harry would deem as "innocent", but is suffering due to cancer. He struggles with the morality of being able to execute killers without any remorse, and his seeming inability to perform murder as an act of mercy to a dying woman who is in pain and has asked him to do so.
Camilla Figg is the woman in question, who worked in the records department at the police precinct. Her friendliness with Dexter allowed him to access files and records on people that he wanted to trace or kill. She is seen smoking throughout and receives a terminal diagnosis of lung cancer. In pain and with only a month to live, she wants Dexter to end her suffering.
He eventually does, despite his mixed feelings and betraying his code, but there is an exchange between Deb and Dexter when they are discussing Camilla's predicament that reflects exactly how the end of the series plays out. Deb states that if she was ever like that she would want to be put out of her misery. She even specifies "pull the plug" at one point.
More than five seasons later, Dexter does that for her.