I do not own Xena or Percy Jackson. This discounts the Heroes of Olympus, and changes the prophecy Rachel gives.
"War's Chosen will return at the sacrifice of War. The Gods shall fade without War, but War will not return to Olympus without his Chosen as his Queen. Only the joining of a child of War and Sea can restore the God of War, place him upon the Throne of Olympus, and save the Immortals of Olympus." Rachel collapsed. Percy and Nico caught her.
"What happened." Percy looked to Apollo, and the God of Light looked like he just saw a ghost, trembling in fear. "By Zeus, Ares has found her corpse." Apollo flashed out.
Percy said, "We need to take her to Chiron, right now."
Rachel blinked, "What happened?"
"It looked like you gave a prophecy." Nico said. "We need to tell Chiron, that prophecy sounded bad, I mean Apollo freaked out."
Percy agreed and the demigods and the new Oracle ran back to the Big House. Chiron was looking over some scrolls when the teens burst in. "What's happened?" He asked after seeing the worried faces of the demigods running in.
"We've got a new prophecy," Percy said, "and it looks like it's going to happen soon."
"I see, tell me the prophecy then, I'll need to hear everything." Chiron said.
Percy said, "War's Chosen will return at the sacrifice of War. The Gods shall fade without War, but he will not return to Olympus without his Chosen as his Queen. Only the joining of the a child of War with Sea can restore the God of War, place him on the Throne of Olympus, and save the Immortals of Olympus. Then Apollo flashed away to tell Zeus."
Chiron was pale when Percy finished. "He found her corpse."
"Apollo said the same thing, but who found this corpse, whose corpse is it, and how are they going to sacrifice Ares." Annabeth said.
"No no no," Chiron shook his head, "Ares is the one who found the body, and he will sacrifice himself to bring her back. Or, more accurately, will sacrifice his godhood and immortal existence to bring her back." Percy and friends were stunned. "Hades cannot resurrect the dead, not without a price that any who cares for him would let him pay, but the other gods must condemn themselves to a mortal existence, no power, no immortality, to bring the dead back to life. Ares is the only god to ever do so, and that was to bring back two people his Chosen loved. There is no doubt that he would give everything to bring her back, therefore he must have found her, no god wants her back, and would keep her hidden if they knew where her corpse was. Ares would be incapable of getting to her."
After a moment of stunned silence Annabeth asked the question, "Who is she."
"She was Xena, a mighty princess, forged in the heat of battle. She was what was called a Chosen, a mortal taken under a gods wing and trained by them. Many gods had at least a few Chosens over the centuries, Ares only had one. After the gods she killed reformed, the practice was banned." Chiron sighed. "Xena killed half of the Olympians and two of the big three single handedly. Ares ultimately sided with her, and will never side against her again."
"We are talking about the same Ares here, right? The complete jerk god who only cares about power and violence." Percy asked.
Chiron sighed, "Shockingly, yes."
After a few minutes, Percy spoke up, "Alright, so I guess it's up to me and Annabeth to get Ares to become a god again."
Chiron shook his head, "Athena may be the Goddess of Battle and Strategy, but she is not War. Athena has never been called War, only Ares. That means it must be a child of Ares. Percy, if you could come back tomorrow, I'll have more information."
The kids agreed and left, discussing this new quest.
The next day, Chiron sent Grover to get Percy and Clarisse. When the demigods showed up, they were greeted by the sight of Zeus and Athena talking to Chiron. The two gods stood and walked to the teens. "Percy Jackson, Clarisse la Rue, your quest is simple." Zeus said, ignoring their attempts at greeting. "You are to find my son and the woman he is with, and convince him to return to Olympus by any means necessary." The king of the gods disappeared in a flash.
Athena spoke solemnly, "Percy, this will be the most dangerous quest you have ever been given. I know you have fought Ares before, but he will be nearly completely different from when you faced him. He will not give in or stop until he's incapacitated, and he will fight with more skill than you have ever seen before. And Xena is well known among the gods as the greatest warrior in history. You can't defeat them together, no one can. And Xena is the one you must convince to become a goddess, Ares will not return without her by his side. I would avoid mentioning myself as well, as I was the reason she killed gods."
