These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Detective Norman Stansfield is a DEA Agent who takes advantage of his position to terrorize, extort and kill who he wants. On a drug bust, Stansfield decides to get high on drugs and, while playing classical music, slaughters the whole family, including the couple's baby son. His only emotion over it is how he'll explain the death to his superiors. Stansfield, when confronted by the couple's 12-year-old daughter later, think that she's there to kill him, but when she can't bring herself to and breaks down crying, Stansfield asks her if she enjoys living. When she says she does, Stansfield makes clear his intent to kill her, saying he takes no pleasure in taking the life of someone who doesn't value their own.
Narm: Léon's slow motion, cross-eyed yell right before his room gets hit with a grenade.
Nightmare Fuel: Norman Stansfield: A drug-addicted psycho with the law on his side.
Special Effects Failure: Stansfield discovers the grenades in Leon's vest. Cut to outside, where one of the cars blows up before the explosion happens in the building itself.
Tear Jerker: Léon's death. A rewatch of the movie (and a reminder of his status as The Woobie) only makes it worse.
The Woobie: The main characters. Léon especially, who even as a hired killer, behaves rather childishly and innocent. He drinks milk, waters potted plants and watches old musicals with the look of a fascinated boy.