Jason Grace

Jason Grace is the son of Mrs. Grace and Jupiter. His sister is Thalia Grace (a hunter of Artemis). He was conceived while Zeus was in his Roman Form, Jupiter, making him a Roman Demi-God. He and his sister are the only known Demi-gods to be born from the same mortal parent and be from the different aspects of one god.

Jason is the apparent leader of the Roman Camp as he was traded for Percy Jackson who is seen as the leader of Camp Half-Blood. He is one of the seven mentioned in the new Great Prophecy.

Speculations:
 * If Jason got his tattoo when he was 3 and each line on the tattoo represents a year, that would put Jason at the age of 15.