So there is a new book that is coming out in February a friend of mine wrote it it is called These Chains that Hinder Me her name is Crystal Owenby it is about gaurdains of elements. There is ace( the gaurdain of darkness) light(the guardain of light.) Saphria(the guardain of phyic powers.) All three are silblings ace and light are twins whereas saphria is the older sister. Scince ace is the gaurdain of darkness he cant love or feel anything besides pure hate and despair. Then yakumo comes along( the gaurdain of love.) And frees ace from his somewhat of a prision.