The Cruel Prince
This is the first in a trilogy.
The book begins with Jude's parents being murdered by her mother's former husband...who just happens to be a redcap from Faerie.
He brings Jude, her twin sister Taryn, and their older sister (and his daughter) Vivi to Faerie where he loves them and raises them all as his own daughters among the faye gentry.
Jude is a fighter, so when she is challenged by none other than one of Faerie's own princes simply because she is mortal, she finds it hard to back down.
And of course, nothing is what it seems!