The Darker Side Of Feas, anyone know? Options

I've been reading 'the temple of shamanic witchcraft' and the author put in a section on the fea realm. I've tried visiting it, but no luck. It seems like I need to be more relaxed and concentrated on one thing other than the drama and bull shit going on.

The author said something about the dark side of feas, how bad they can be. He said that if he told us, the readers, then he thought he would turn us away from them. This leaves be curious. Does anyone know the dark side of them?

I have never worked with them, so take what I say with a grain of salt. I have heard from others that some fae can have a dark sense of humor as trickster spirits. Hopefully someone who knows more about the subject can be of more use.