Sky was the former prince of Eraklyon. However, in the 1st movie, The Secret of the Lost Kingdom, he was crowned as the new king. Although he is still crownless.
Sky is a brave specialist, and is willing to save others in need of help and he is also loyal to his friends. However, he is also energetic and not so serious, despite that he is a king. He gave the Seal Of Euraklyon in season 4 for some money to get a flat for him and the Specialists.