I did a search on the forum quickly and couldn't find a place to see if this had been discussed. But one of the things I liked about the Ravenloft 3.0 book was the concept of Innocence.
Recap for those who haven't read it: since alignment, especially the moral axis, is meant to be vague in Ravenloft and most powers to divine or detect alignments tend to fail or be mislead. So instead, there is a more discernable metaphysical representation of "goodness", Innocence. As its name suggests, Innocence represents a character with an unblemished soul; Innocence is very easy to lose and, once lost, can never be regained.
I really feel the concept of Innoence drives home the tragedy side of the gothic horror setting in Ravenloft. After all, it's possible for a Good character to fall, but they can be redeemed (albeit with greater difficulty than usual in Ravenloft); and that fits redemption type stories well.
But it doesn't fit the true tragic stories of loss: the idea that certain actions can never be taken back, that once some sort of purity is lost, it can never be regained.
It's also intruiging to think about the way that Innocence detaches from the moral axis. After all, an Innocent character can technically be Evil (as long as they've always restrained their nature); conversely, a Good character can have lost their Innocence in one moment of lack of control and forever regret it.
I think it could bring a lot to the table in terms of story and roleplaying potential.
As to how one might mechanically represent it: I concede I'm not so sure about that one and it sounds a lot harder to do. Perhaps it could be represented by another piece of OOC equipment? e.g. "Your PC's Innocence". It could be an item that is activated to give whatever Innocence bonuses and penalties the books mention; while a secondary activation would allow a PC to destroy their Innocence, to represent losing it.
(Scripts or DMs could also be used to determine the loss of Innocence due to certain events -- e.g. attacking peasants, that sort of thing.)
Anyway, just thought I'd throw this out there...