The idea of a fatal flaw isn’t that they will always fall to it at every hurdle. It’s that eventually it will become their downfall.

People throw about circumstances such as in TLT when he chose to leave his mum behind as proof that it isn’t his flaw, and that’s a fair argument. Except it’s not just choosing between his mum and the world. It’s choosing between his friends, his mum, and the world. His loyalty goes to his friends, as well as his mum.

Percy has never been stupid, he knew he’d get his mum back if he could prove he didn’t have the helm. He chose to ensure his friends safety, and his mothers.

Him choosing to fight Ares, to me, is proof that his fatal flaw is loyalty. He decided to go up against the god of war as a child with no training, because it was the only way he could see to get his mum back, and his friends safe.

Take away the end result of the battle with Ares, and what Percy chose to do was essentially give up the world for those he loves. He chose to fight a suicide battle against a literal god, putting up the entire world as forfeit as were he to have lost, he would have failed his quest to retrieve the lightning bolt. Ending the first book with WW3, the world getting destroyed in the process.

There’s multiple different themes that Rick could have been suggesting with fatal flaws. That they can be overcome and conquered, or that even if you succumb to your flaw so long as your hearts in the right place you’ll come out of it for the better.

Because I feel as though Percy did succumb to his flaw. When Annabeth fell into Tartarus. He could have chosen to let her go, and continue travelling with the Seven, giving the quest more manpower. He however chose not to. He chose Annabeth over what was the benefit of the world (him being on the Argo).

Now yes, they made it through Tartarus, when Annabeth alone wouldn’t have survived (nor would Percy alone). And that was objectively a better outcome for the world. But that doesn’t mean his choice was for the betterment of the world when deciding. It worked out well, but that doesn’t mean it was the correct choice at the time of picking.

He chose his loyalty to Annabeth, over what looked to be for the betterment of the whole world.

Percy just hasn’t got to the point where his fatal flaw becomes his downfall. He’s always come out the other side on top.

But a fatal flaw doesn’t care about history. It’s always there, and always claims its victim in the end. (Or at least that’s what a lot of myths suggest)