Ok so hear me out. More monsters went after Thalia than Percy, right? I dunno if I misheard this or Iāve read something and my brain has registered it as cannon, Iām pretty sure it was in the series, but I heard āHades set off monsters to chase Thaliaā or something similar. So, why didnāt Hades set off monsters for percy?
well for this you gotta go back. Like- 1930s back (I think you might understand where Iām getting at here). Think back to when Nico, Bianca, Maria and Hades where in the hotel. Zeus found out and sent a lightning bolt upon them. Hades protected the children, but Maria dies.
Now back to the present. Zeus has had two kids of his own, and eldest daughter and a youngest son, but obviously we donāt know about Jason till later on.
Hades is angry. He hasnāt forgotten that Zeus commuted murder and Attempted Murder on Maria and the children.
So he sends the monsters out to chase Thalia. To give Zeus a taste of his own medicine.
You may have also thought āwhy didnāt the monsters attack percy more then?ā Because (as far as Iām aware) Poseidon didnāt do anything concerning this, so hades would have had no reason to go after percy. Plus, percy only got claimed once he was at camp. Thalia never made it to camp, but they still knew her heritage.
Luke figured out (to some degree) that Hades was angry at Zeus for having kids (he wonāt know about the Di Angelo Siblings) and therefore braking the promise. So he takes his anger out on Thalia, not Zeus. Another strand that sent Luke on his path to take down the gods for corruption.
if Thalia also realised this she wouldāve had a higher chance at joining Luke OR she did realise this and that was one of the reasons/reason why she hesitated before rejecting Lukeās proposal to join him.