The second episode, in which a couple therapist encourages a man to murder his wife and looks perversely pleased when a splatter of blood hits her in the face.
Another one opens quite nicely, with a family photobook, telling the story of a young man who loved animals and a young girl who was the prettiest in her school... Jeffrey Dahmer and one of the Manson girls.
We have Joe coming home and finding a bloody, psychotic Ariel with an axe in her hands.
And let's not take into account the Libra Killer or the Halloween episode 'Bite Me'.
Also disturbing were, in season 4, her dreams about what happened to Cynthia's daughter.
There's also the fact that just killing someone isn't enough, especially if they know about the afterlife.
The idea that dead serial killers can continue to possess people for eternity?
The season one episode with the "Good Samaritan". Allison knows that he's a horrific Serial Killer who kidnaps, rapes and murders young women (who all go with him willingly because he seems like such a Nice Guy), but she can't do anything about it - because it hasn't happened yet. All she can do is warn the first of his victims and hope she'll remember it in seven years.