Who is Caspar from Sapphique and what is their importance?

Caspar is Prince Giles's stepbrother and the stepson of Queen Sia. Caspar does whatever the queen tells him to do. Caspar is in love with Claudia and tries to get her to marry him. Claudia shuns Caspar's advances.

When the illusion of th realm disappears, Caspar is heartbroken. He cannot believe that is stepmother is really old and decrepit. Caspar cares for the queen as she passes away.