http://www.fanfiction.net/s/8661690/1/MercilessThis is one of my favorite fics out there. Not only does it capture the dark theme, it also reminds the reader that just because Corvo spared his targets doesn't mean he's "good" or even "merciful". Heck, he may even be worse than a High-Chaos Corvo. Fates Worse Than Death, stuff like that. It's well-written and deep. If you've played the game, you're going to enjoy the heck out of this one. WARNING: Low-Chaos Ending Spoilers