When Percy, Annabeth, and Grover were going to Aunty Em's aka Medusa Garden Gnome Emporium
When Percy, Annabeth, and Grover went to the Santa Monica beach in Los Angeles because a voice in the water told Percy to go when he was in the Mississippi River. Then Percy followed a green light in the water.
When Annabeth, Grover, and Percy went to Hades' palace.
When Percy was giving Zeus his lightning bolt back and Percy was saying house Hades' palace looked like Zeus' palace.
Percy talks to his father, Poseidon, for the first time ever since he was a baby.
When Percy goes back to camp and Luke wants to talk to him and we find out that Luke is the one who betrays Percy.