S L Bradbury: 2 books

 Young warrior. Brave girl. Precocious little sister. The twins must fight for their lives!   In the woods on a backward planet, called Xanis by its natives, an attack is brewing. A peaceful hold falls to enemies and House Lonmere’s extensive family...

Young genius or monster? Loving father or Rzash operative? Telepathic cop or savior? Juvenile rascal or Song planet? The answers abide in the darkness and the silver. The planet Xandor-II is lost to the Rzash Empire, but Tarik escapes with a piece of it. Now his...