Percy was fighting alongside Annabeth against Kronos. He turned around for less than a second when he heard a scream. It was a scream he'd hoped to never hear. It was Annabeth's scream. He watched as Kronos crushed Annabeth, instantly killing her. He watched as her limp and lifeless body dropped to the ground. He screamed in rage, and was soon surrounded by a hurricane stronger than any his father had ever made. He walked up to Kronos with a cold and expressionless face. He swore that he was going to kill Kronos. He just laughed at his statement. All the campers and gods watched and his hurricane grew even more powerful and lifted both Percy and Kronos into the air. With one last scream of rage Percy plunged Riptide into Kronos's heart, twisting it as he pulled it out. He howled in rage and pain, before exploding into dust and falling to the ground. Percy dropped in exhaustion.

After that Percy slept for a week. When he woke up he ran. He ran, not bothering to grab any provisions. He just wanted to see Annabeth in Elysium. He ran and mist traveled to Antarctica. When he arrived he lay down on the ice and willed water to freeze him just below the surface. He lay his sword across his chest (in sword, not pen form) as he felt himself freeze over.

When the campers and gods realized he was gone none of them knew where he went. After ten years of searching, everyone realized that they would probably never find him out he was dead.

Now, 33 years later (assuming that he ran away in 2017) two demigods on a quest in Antarctica find a person frozen in the ice. Who is this mysterious person in the ice? And why is he here?