Lots of back story to the idea. The character is normally a rather good-spirited paladin. There was an off-shoot idea of the world his family is from where things played out differently and the good guys were actually the bad guys and lots of roles were switched and reversed. So this is a sort of 'evil' or 'darker' version of our holy crusader, perhaps having grown up to be a slayer of all wrongs without mercy type of character. (The one most likely to fall due to their extreme zealtory)