Cerulean is a weak, but free party member and your pet dire wolf. Cerulean is automatically added to the party if you name your character "Stark".

He can't equip any items, has no skills, no dialogue or Relationship Points but does make the beginning easier until you have a full party, however Cerulean also takes more experience to gain levels so as you progress in the game he will lag further and further behind other party members.