Percy Jackson and the Olympians : the lightning thief chapter21

Yay!! Percy's mom is back but first he went to Olympus and in the next chapter he is going to camp half-blood the prophesy is almost clear but who is the freind that was destined to betray him is it grover or annabeth or clarisse or connor stoll or travis stoll and etc. Many answers to find out in the next and last chapter of the lightning thief book