Because you like Paulie Pennino in Rocky Series

Brilliant, violent, and only a little insane, the Joker doesn't listen to anyone except the voices in his head. See them in DC Extended Universe.

Puss In Boots is a suave, honorable ladies man/cat who's not above playing cute to get you to let down your guard. See them in Shrek 2.

Some say to survive in Underland you need to be as mad as a hatter–which, luckily, he is. See them in Alice in Wonderland.

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.