In hunter x hunter, Hisoka, who was one of the antagonist villains, has shown a very psychologically weird behavior, especially towards really strong opponents. Hisoka is always looking for stronger opponents who can challenge him (or opponents who he thinks might get strong enough to challenge him, given the right amount of training). Sometimes, if the opponents that he wants to fight with seems really strong, Hisoka gets turned on and that just seems super weird. (Usually the logical thing is to get rid of all possible obstacles but rather he loves the challenge, and the stronger the opponent, the more excited he gets [even if the battle might be the end of him]).
Is this behaviour natural in the real world, or is it just an anime/manga villain characteristic? Because I have noticed that other anime characters have shown this behaviour and most of the anime characters were villains (examples are the pillar men from Jojo).