Well, most of my knowledge of him has been gained through cultural osmosis, the 'Knightfall' storyline, and bits and pieces here and there. I do know, however, that Jean-Paul is 'dead' (quotes because this is comics, after all), and has been replaced in the role by some religious fanatic guy who wants to do penance or something. This sucks, because A: Jean-Paul is an interesting character with a fair-sized following in his own right, and B: one of the things that made him/makes him interesting is that he himself is not particularly religious, at least as far as I can tell. You won't catch him screaming about God's wrath or whatever - he's a regular guy without any particular religious views who learned midway through what he thought was going to be a regular life that he was the son of and successor to a deadly angel-of-death-themed assassin in a long line of assassins who served an obscure religious order. There's a concept with some depth to it - replacing it with the standard 'I must purge with holy fire' stuff is just paying lip service to a cliche.