Chaos (The Ultimate Crossover)

Olympus Has Fallen.

Hi. My name is Percy Jackson. If you thought that after defeating Gaea, we were safe, you were very wrong. You see, the thing with demigods is that we are never safe. After we learned about Magnus (Annabeth's homeless cousin [Don't ask]), everything came crashing down. Literally. About a year ago, Olympus fell.
                                                                    *One year ago*
"Thalia, stop!" I said as we climbed the old fashioned way to Olympus. " I'm tired!"
"I don't really care. I just want to get this over with" Thalia Grace said. Thalia was the daughter of Zeus so you see that if you even argue, you become roast beef. So naturally I did whatever a powerful child of Poseidon like me would do. I kept on going. The reason we were there in the first place was a real tragedy. And no, I'm not refering that my favorite show Pretty Little Liars was going to be canceled in its 7th season. (Don't judge me.) No, it was something far worse.
A year ago, the hunters were pursuing Lycaon through the woods in Scotland or something. When they found him, he ambushed them with werewolves. All of the huntresses died. All except Thalia. She was badly injured but she was found by some people. She said she woke in a hospital wing.
A kid with pale hair and another with jet black hair were watching over her. So she did what she knew best. She hit them square in the nose. They took out some sticks (later I realised that they were wands) and began shooting spells at her. She ran through the door and found herself in a hall of a castle.
"Scorpius, where do you think she went?"
Don't know, mate. Perhaps ..." He walked towards her silently. "Hey Albus. I found her. She's knocked out cold."
They cured her and brought her here.
"We're here, crybaby" Thalia said.
Olympus was a wreck. Everything looked like it was stampeded by hundreds of elephants. We began walking towards the throne room. A heated discussion was taking place from what we heard from our safety outside th doors.
"You are all stupid. Can't you see what really is happenning here? Chaos has risen from the pit. Just as Amara has taken place beside her brother. It all is coming into place just as Delphi predicted.
'The Darkness will be light.
The Pit will rise
Chaos will reign
Olympus will fall.'
"Don't you see, father. We are doomed." Athena said as lightning boomed.
"Yes but do you rember what else she said?
'The Heroes behind Shadows will come,
The Hunters will aid,
The Children of Hecate will betray her,
The Heroes of Olympus shall Rise to Power.
The heroes of the mirror will come to restore order.'" Zeus said.
"Hey talking about heroes, let's meet Thalia Grace and Percy Jackson who are just outside our door" Apollo said gleefully.
Shit, I thought. The large bronze doors opened. The worst fight was taking place. Poseidon and Zeus were at each others throats. Artemis and Apollo had drawn their bows. Aphrodite and Hermes were arguing. Athena and Ares had swords and shields out. Everything was chaos. Suddenly a little cry was heard over the commotion.
"Calm down, please!" Lady Hestia cried. Everyone stood still. We were watching how she slowly vanish. The hearth and Olympus were gone.