Caspian grew up very much on his own, although guided by his mother through the early stages of life. As a young  pup, he soon discovered he had a natural affinity for a) befriending other animals, and b) finding his way even when no light was given. Although he remains unaware of his twin's presence in his life, in as much as the twin never reveals himself to anyone, there remains a psychic link between the two. Xerxes is fully aware of this attachment, and whilst he can neither be described as good or evil, there are times when he uses this ability to suit both needs. If evil doings occur, it is out of spite and jealousy of Caspian's survival, whilst any good actions are to preserve his own 'existence' on the world. 

Caspian can sometimes be found wearing a blindfold as he feels safe enough to walk without sight This is only because of his psychic link with his brother (that he is unaware of).