In Percy Jackson and the Olympians: The Lightning Thief by Rick Riordan, two of the main characters are Percy Jackson and Grover Underwood, Percy’s best friend. When they are at a museum on a school trip, Percy is attacked by a Fury, and uses a pen, which turns into a sword, to fight. However, he faints and wakes up to find that he is Poseidon’s son; his friend Grover is a satyr, half human, half goat. Grover, who is very sensitive, can smell monsters and sense people’s emotions. He is Percy’s protector, and must watch out for him. If he successfully protects Percy, he can get his searcher’s license.
As time goes on Grover makes some mistakes, like not bringing Percy back safe and sound the night the Minotaur attacks. However, despite the mistakes he makes, he does get Percy and Annabeth home safely. Beyond this, he longs to find Pan, which is a risky quest and from which no other satyrs have come back alive. Although he has fumbled along at points, his greatest strength is his ability to read emotions. Grover relates to Percy because they are both outsiders and they need each other. In addition, they are connected by an empathy link, which makes their relationship that much closer.