Because you like Patch Adams in Patch Adams

Hell hath no fury like an evil fairy scorned. See them in Maleficent.

When the Sorting Hat touched Draco Malfoy's head, it placed him in Slytherin, a house that has turned out more dark wizards than any other. See them in Harry Potter Series.

Severus Snape is a misanthropic potions teacher with a vindictive streak. See them in Harry Potter Series.

His murderous megalomania aside, Loki is quite charming. Just don't mention his strapping older brother; he's a tad jealous. See them in Marvel Cinematic Universe.