* Responsibility: Percy feels responsible for Thalia's fate. He knows that her death was caused by a misunderstanding and that she was trying to protect her friends. He blames himself for not being there to help her, even though he was only a baby at the time.
* Connection: Percy sees himself in Thalia. He feels like she could have been his sister, and her death makes him realize the fragility of life and the potential consequences of his powers.
* Loss of Innocence: Thalia's story is a harsh reminder of the world's danger and the sacrifices people make in the fight against the forces of evil. It shatters Percy's initial sense of innocence and makes him realize the real cost of being a demigod.
* Fear of the Unknown: Thalia's story also brings up a fear of the unknown for Percy. He doesn't know how his own life will play out or what dangers might await him. He fears he might be destined to suffer the same fate as Thalia.
Percy's guilt and hollow feeling are a testament to his empathy and sensitivity, even as he grapples with the complexities of his own existence. His emotional reaction to Thalia's story foreshadows his journey as a demigod and highlights the internal struggle he will face throughout the series.