What teenage boy wouldn't want to be left alone on a deserted island with just one other person—a teenage girl—for company?
Try Mau. The wave at the beginning of Nation changes Mau's entire life. It kills his whole family and causes him to hate the gods for allowing this to happen. Can you blame him? What Ataba the priest sees as the callous, blasphemous acts of a demon boy could also be seen as the totally normal acts of a boy who's going through the five stages of grief.
The minute he returns to the beach, Mau shifts into defense mechanism mode. "He felt himself become two people" (2.22). He sees himself as Locaha, the god of death, impassively disposing of the bodies of his friends and family that have been left scattered on the beach. We never hear him mention burying his mother or father, although he must have done these things. The enormity of it all forces him to repress these memories so much that he can't even remember what his mother's face looks like and he can't cry. (And no, we're not crying either. We have sand in our eye!)
Shortly after performing the funeral, Mau enters the first stage of grief: denial. "An island full of people could not die. [...] [Mau] was dead! And his spirit had come back home, but he couldn't see out of the spirit world" (2.91). Thinking himself dead and everyone else still alive is the ultimate in denial. Next is bargaining, which Mau does when he saves Daphne from drowning. "No one goes alive into the dark. I served you, Locaha. I walked in your steps. You should owe me this one. One life back from the dark!" (3.133). He's literally making a deal with Death here. We'll admit that Mau never seems that depressed. He does almost give in to death a couple of times, even though we wouldn't say he's suicidal either. Still, we'd say kind-of-suicidal is an adequate substitute for depression. (Plus, he seems a little too busy to be depressed.)
What's that? You say we skipped anger? Pick any random page, and you're likely to see that Mau is angry, especially at the gods. He yells at them all the time. He's so angry that he practically stomps all over the book—right up until the end, when he finally reaches acceptance.
And here's the cool, growing-up part: without the wave, he would be a different person than he is at the end of the book. When it comes down to it, he wouldn't change a thing.
Since the wave created some pretty big, immediate problems for Mau, it's easy to forget that he was in the middle of an important rite of passage in his culture: the transition from boyhood to manhood. Mau spends the rest of the novel in a kind of in-between state—no longer a boy, not yet a man. Despite that, he manages to defy expectations and become a great leader of his people. (Plus, he avoids the "thing with the sharp knife, where you didn't scream" (1.101), which we hope is nothing like this.)
Even though he's not a man, Mau is already a great leader. He devotes himself to his people, a character trait that will stay with him throughout his whole life, as we see in the book's epilogue. He doesn't care what they think of him, even the ones who call him Demon Boy, but he cares about them: "he wanted to be everywhere and do everything" (9.26).
Since we don't know what Mau was like before the wave, we don't know for sure how much it affected him. Still, his ethic of caring could very well be the result of the tragedy of the wave. Take his mantra, "Does not happen!" (3.141). He's determined to not let tragedy befall him or his people again.
Of course, people tend to take advantage of this. Daphne wonders, "Why did everyone want him to do things?" (9.72). She sees similarities between Mau and her own father, who threw himself into his work after the death of his wife, Daphne's mother. Her dad was "trying to fill the hole inside with work so that it didn't overflow with memories" (9.26).
Whether he's doing it out of grief never resolved or a devotion to the growth of his people, Mau knows that he will always be this way. He says, "I'm the little blue hermit crab. [...] I will not be trapped in a shell again because [...] any shell will be too small" (6.251). Mau will forever be in this stage in-between boyhood and manhood because he does not see "manhood" as an ultimate goal. He sees everything as an opportunity for growth and change.
We're not sure whether to label him "boy" or "man," but it doesn't matter. He's brave, he's competent, and he "will fear nothing, ever" (10.66).
As Mau grapples with his identity, he starts hearing voices: the voices of the Grandfathers. We're hesitant to say that the Grandfathers are speaking to him, because he might just be talking to himself without realizing it. Both cases have valid points. Let's hear the evidence.
Plaintiff: The Grandfathers are Talking to Mau
Exhibit A: The Grandfathers implore Mau to bring up the god anchors. This starts a chain of events, ultimately leading to the Grandfathers being freed from their cave. "The Grandfathers had been stuck in this moldy cave forever. They wanted to get out!" (10.128). Mau would have no way of knowing this on his own.
Exhibit B: The Grandfathers no longer speak to Mau after the cave has been opened and their ashes released into the air.
Exhibit C: They want beer. Mau doesn't even drink the beer, so it would be the last thing on his mind after a tragedy such as the wave.
Closing argument: "The gods are in everything we do" (5.86).
Defendant: Nah, man. Mau is just talking to himself.
Exhibit A: Mau says that "He'd never heard [the Grandfathers] before" (2.57). He also never mentions stories of anyone else hearing the Grandfathers either.
Exhibit B: The Grandfathers are Mau's pep talks to himself to keep himself alive. They tell him he doesn't deserve to die, and he needs to get off his lazy butt to keep Nation alive.
Exhibit C: Mau wants to know "How did [the Grandfathers] get into [Mau's] mind? How did they know things? And why didn't they understand?" (4.102). Mau's really the only person who knows what's going on in his mind. And he sure doesn't understand what's going on in his world, which has been turned on its head.
Closing argument: "[The Grandfathers are] just parrots" (5.71).
Now that you have the evidence, you be the judge.
Although Pratchett gives few concrete examples on what Mau's people's faith was like, we know it revolved around the gods of Air, Fire, and Water. (Not Earth, Wind and Fire, although Milo's son Guiding Star might appreciate this one of their hits). We also know that Mau's people believed the gods did things for them. They led passive lives rather than believing that they made their own destiny.
After the tragedy, Mau breaks it down: "Either the gods are powerful but didn't save my people, or they don't exist and all we're believing in is lights in the sky and pictures in our hearts" (6.248). He thinks to himself, "The gods let you down. When you needed them they weren't there. [...] To worship them now would be to kneel before bullies and murderers" (7.23).
For a long time, Mau is furious. He yells at and taunts the gods. In fact, he's no mad that it's hard to believe that he no longer believes in them. How can you be so mad at something you don't think even exists?
Or maybe he's just mad at Ataba the priest, a physical representation of everything Mau hates about the gods. Ataba doesn't make it easy, taunting Mau, calling him demon boy, and making him feel like less of a human being. Mau almost buys it: "Maybe I have no soul at all, maybe the darkness inside is my dead soul" (4.115).
But in the end, Mau decides the gods are just impractical. He wants to take matters into his own hands. Or into his own mouth when he, er, milks that pig. He tells Ataba, "You can pray to the gods to make it rain milk. I think you will find lying in the muck is more reliable" (5.83).
Mau's still a little insensitive at this point. When Ataba responds, "Are you trying to smart, boy?" (5.84). Mau retorts, "Trying not to be dumb, sir" (5.85). (Hey at least he's polite.) He also tries to be sensitive, avoiding voicing his atheist beliefs when the situation is dire. He equates his (lack of) belief as a spear, saying that "You do not throw a spear at the widow, the orphan, the grieving" (7.24).
Or maybe he just wants to eliminate the world of ignorance. He wants to learn and he wants to spread knowledge, but part of him knows that absolute certainty about the gods will never be possible: "Perhaps [gods] do exist. I want to know why they act as if they don't" (6.215).
Here's our final thought: Mau thinks he has no soul, that inside of him is "darkness" or a "dead soul" (4.115). But maybe—just maybe—but deciding to believe in himself rather than in absent or fickle gods, Mau grows his own soul.