Sabastion is Grampa Lary and Grampa Wayne's amazing, but very old dog. Cass treats him as if he were her own dog. She walks him for her grandparents and feeds him.
Sabastion is blind, and in the third or fourth book becomes deaf. But he has the keenest sense of smell. They call him Sabastion the Seeing Nose Dog. He has helped Cass with many things, including helping her with Midnight Sun troubles. Sabastion is a very loving dog and loves people.
Unfortunately, in the fifth book he is dead, much to Cass, Max-Ernest, Grampa Wayne and Grampa Lary's despair. R.I.P. Sabastion!