Looking for stories where good characters turn bad/evil, especially manga which are interesting and have strong characterisation, good plot, etc. *Turning bad/evil as in: joining up with the other side, committing various crimes, etc.
Not looking for manga which contains tragedy unless the author's really good at utilising it as a plot device instead of as a shortcut of ending the manga. No pure romance either 'cos I can rarely put up with nothing but romance(As in without drama, comedy, etc).
Can be shounen, seinen, shoujo, josei, etc. I don't really care for the genre: just that the story has to be good.
Black Lagoon - Everyday salary-man and a few others get kidnapped while on business by South-East Asian pirates (the modern type), he gets Stockholm Syndrome and ends up joining said pirates mostly as a translator.