The Sacrifice
(The Fey #1)
By Kristine Kathryn Rusch (1995)

When the most powerful ruling family in the world attempts to conquer a tiny, seemingly helpless island kingdom, they meet forces they never knew existed, and face an epic battle that changes everything.

It’s ten books long, over 1.3 million words and a series I had put off reading for about a year after purchasing the series.