Uprising

[Book 3]

Perseus (Percy) Achilles Jackson. The Kelp Head. The Seaweed Brain. The Rogue.
With the new Prophecy looming upon them, the monsters of Alaska are the least of the Argo II crew's problems. Percy Jackson holds no problem with these eternally regenerating foes, but the others are far less trusting of the mythological brutes. But if they want to survive, they will have to work with the monsters of the Land Beyond the Gods.

Because in a survival of the strongest, they don't have a choice.