Banner of souls

by Liz Williams

One of Mars's most elite warriors, Dreams-of-War, must travel to Earth. where she has been assigned to guard a very special child. But someone else is speeding towards the same planet with a different agenda. She is Yskatarina lye, daughter of an ancient clan from a ghost-realm at the edge of the solar system. The result of an experiment gone wrong, she has been reborn with a terrible destiny: To seek out one little girl from the teeming hordes of the galaxy and kill her.

See on goodreads | librarything