Polaris and Sirius are brother and sister (Sirius on the left and Polaris on the right). They are genetically very similiar and are almost the same size, sharing many features although it is not hard to tell them apart. They are also naturally born Proteus ships, much like Saya was.
They are typical kids, learning, playing and fighting a bit too.
These two are set to make their debute in Proteus Unbound Book 7, the first book of the Legacy Saga and to say readers will have a rollercoaster ride is an understatement when you meet these two.