Hmm I can't say I would change my own heart, not because I think I'm perfect, but more so because we're all a little twisted I believe and a little darkness is good to balance out the light, Yin and Yang if you will. It's when the darkness starts to take control, that's when a problem ensues, but I find life to be the journey to learning how to control and balance out our inner darkness. If we're going by people we know, I don't think there's a person I'd change because I'd only want to change a heart I view as truly evil and irredeemable, thankfully I don't think I know anyone like that. If we're going by anyone in the world? There's plenty of corruption in the world, so I don't even know where to start. police, lawyers, news reporters, congress et cetera. Most jobs of power are more often than not tainted by corruption. If I was a Phantom Thief, I would essentially slowly try to reform the world like they did in the game.