This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Jodi Picoult
The book is about a school shooting which is scary enough for most, and is mostly a Tear Jerker. But there is one part where during Peter's trial, the prosecuting attorney presents evidence in the form of the security tape from the day of the shooting. It shows the shooter, a boy named Peter Houghton, shooting a couple of people in his cafeteria. He then stops, sits down at a table, pulls a box of cereal, milk, a bowl, and a spoon from his backpack and has himself some breakfast. After he finishes, he cocks the gun and continues on his rampage.
Also, Det. Ducharme's description of walking through the hallways of the school, where he sees some of the victims of the shooting, some injured, some dead.
Peter's suicide. He shoved a sock down his throat.
Matt. You know when a person's more evil than a kid who shoots up a school, you're in trouble.
The scene in The Pact where Chris dares Emily to go into the boys bathroom at a McDonald's. Emily is cornered by the creepiest janitor in existence, who proceeds to molest her. Her mother is right outside the door, and has no idea what is happening.
Because of this traumatic event, when Emily tries to abort her baby, she suffers a breakdown when the male doctor tries to begin the procedure. Can you imagine, after suffering with such a heavy burden for years, having to relive the experience, however tentatively connected they may be?