Another great dark series by Kathryn Ann Kingsley.  I have yet to be disappointed by any of her writing.  Her dark characters are truly dark, not merely tortured emo boys.  

She creates landscapes that are ancient and eternal and incomprehensible .  Magic is cruel but amoral in a true chaotic alignment, whether good or evil but mostly neutral. The human world is intertwined through the world but human protagonists are not powerless or entrapped by their weakness but their very humanity is the key to the world and it's creatures. 

And the love stories are emotional and believable.  The sex scenes are dark and kinky as well, with aspects of BDSM and anal but consent is deftly woven into those scenes.