Who says it was trivialized? The fic I read was in fact a very good and very frightening psychological piece from the POV of one of the killers, not earning sympathy for them but showing how frighteningly ordinary and seemingly logical their thought patterns might have been, even though they obviously weren't. Not all fanfiction is fluffy and stupid. That's exactly the kind of attitude that makes people never take fanfiction seriously as a form of writing.