[quote=@sakurasan]
[@The Muse] But... If they are a sadist, won't it be obvious in the IC if they want to hurt certain people around them?
[/quote]

Yes, some secrets will be more noticeable than others. You don't necessarily HAVE to hide it in you're writing, just from the characters. For example, my character's secret will become very noticeable to the reader once I start writing about it. xD