.Another Character that plays a tiny role is: Annabeth chase:

In the book she also has a powerful tool that was given by her mother. That is her yankees cap with makes people invisible, when they got attacked by Dr. Thorn she gave it to percy so he can become invisible and save her.
She was also captured.
Grover Under world is a major character too:
He and Percy are best friends for life, They have a lot of things in common.

Quote said by Percy was: “ I met her eyes, trying to ask a thousand questions, there was just one message she was sending me though: run”.
This meant that he had a dream or a vision of annabeth captured by Atlas, but when he looked at her all she said was “come quickly I need help.” He was probably trying to ask questions