Sarissa

Sarissa is a Changeling, and the new Lady of the Summer Court. She is the daughter of Winter Queen Mab and twin sister of Maeve. She first appears in the novel Cold Days.

Biography
Sarissa is introduced first as Harry's caretaker and then his date to his birthday celebration, where she informs him of the rules of the Winter Court. In the end of the book she is revealed to be Maeve's twin sister and Mab's daughter, groomed to replace Maeve because of her illness.

Maeve's killing of Lily ended up leaving her as the nearest vessel to be filled and thus making her the new Summer Lady.