Teamwork and friendship is important in anyone's life, especially Percy Jackson's. In "The Sea of Monsters" by Rick Riordan, Percy relies on his friends and teamwork to keep him alive through multiple battles. Rick Riordan tries to help us imagine people working together as opposed to in competition with one another.
Percy is a demigod. This means that he is half mortal, and half Greek God. He goes to camp in the summer for you trains to fight monsters, and goes to regular school during the year. He has to be very careful about monsters in the mortal world, and he hasn't had an encounter until the last day of school. He is in PE playing dodgeball, when all of a sudden the kids on the other team grow to 8 feet tall and start throwing have a bronze falls and encased fire. His friend to Tyson who is a cyclops even though Percy doesn't realize, diverts the attack while Percy runs to get his sword. Without Tyson Percy would've died. This tells us that you figuratively and literally shouldn't fight all your battles alone, and it's always good to have friends by your side.
When Percy gets back to camp after this, he finds that the magical borders keeping monsters out have weakened, and there's only a few kids who stayed year-round to fight monsters. One of them is Clarisse, someone who doesn't like Percy, and he doesn't like her either. In spite of this, when Clarisse was knocked down in battle, instead of fighting the other monster, Percy dashes over to her and gets her out of the way before she is trampled. Clarisse would've died without Percy there to help. This shows teamwork is important even if you don't like your teammates. In the end, you all have one common goal, and you need each other to accomplish it.
Percy has another friend, Grover, who is on a quest to find the missing God, Pan. Before he left, Grover made an empathy link between him and Percy, which means they can communicate through dreams. In a dream, Grover told Percy that he was is big trouble. He was completely trapped and probably going to die. Percy didn't hesitate to say that he would go save him as soon as he could. In that moment, Percy cared about Grover more than the weakened borders at camp. All he wanted to do was help his friend, even though he knew it would be nearly impossible. This shows how strong their friendship is and how much they mean to each other.
This whole book is all about teamwork and helping each other out. Percy needs his friends, and his friends need him. Percy is the hero of the story, but he couldn't have done it with out help.