In fiction, heroes generally try to avoid killing the villain unless it's absolutely necessary. This especially applies to child heroes, who are more prone to Black-and-White Morality and prefer not to use violence at all, let alone kill a villain, no matter how evil or dangerous they may be. Some, however, have no such qualms and are fully willing to kill the villain in order to stop them or protect their loved ones, and seem to have no real problem in doing so if the villain is that evil. This is often a sign that the villain has crossed the Moral Event Horizon that even a child who generally values all life decides they have to be destroyed. This can count as Troubling Unchildlike Behavior if they take too much pleasure in it, but it may simply be used to show the hero's sense of justice or commitment to doing whatever it takes to stop the villain.
Compare Children Forced to Kill, where the child is very unwilling to do this but is forced to against their will, and would likely be traumatized by it afterwards.
Examples
- Kelly in The Lost World: Jurassic Park uses her gymnastics skills to kick a raptor to its death, being the first person to score a dinosaur kill in the films.
- Atreyu in The Neverending Story is a sweet kid but is willing to kill to save Fantasia, as he challenges his nemesis Gmork to fight to the death despite Gmork not knowing who he was facing, and kills him by stabbing him in the heart with an improvised stone knife.
- In Season 3 of Stranger Things, Dustin electrocutes Dr. Zharkov with a cattle prod.
- Done in a particularly infamous scene from Zelda: Wand of Gamelon, when Zelda fatally stabs Hektan:Hektan: YOU'VE KILLED ME!
Zelda: Good.
- My Little Pony: Megan Williams is perfectly willing to kill the villains if that's what it takes, killing Tirac, Squirk and Crank herself, which gives her the highest kill count in the show.
- In the series finale of The Little Mermaid, Ariel kills the Manta's brain sponge by tying it between two pilars, then pushing a boulder onto it and crushing it to bits.
