Riordenverse

Did Percy come to Camp sooner?

Did Hades have to Daugthers or two Sons instead of a Daughter and a Son? Are they perhaps Twins?

Does Percy have more then one Godly Parent?

Perhaps the Skin color of Carter and Sadie Kane is in Reverse?

Maybe Carter and Sadie were subconciously influenced by Horus and Isis without the Gods themselves knowing?

Perhaps Magnus Chase was born a Girl instead of a Boy

So Many Possibilities.....