the guardians of the gods(Percy Jackson)*on Hold*

all of the gods get a guardian that they name and send to do what they want done if they can't do it themselves.
what happens when the last guardian picked is the last one to survive.
what happens when the maiden goddess never made their vows yet.
what happens when the last guardian goes down to tartarus? will he get out?what happens if he does? what happens if he doesn't?
what's the real reason behind Dionysus punishment?
--------------------------------------------------------
set in the first giant war.