Salva is dependent at the beginning of the novel because he depended on adults like his parents to take care of him. In the morning his tribe left him and he was scared, and upset.
In the middle Salva felt bolder. This is because Salva's Uncle was shot and killed by 3 Nuer men. Salva felt sad but then he felt stronger and bolder that before.
At the end Salva feels lucky. This is because he was chased by rebels into the Gilo river infested with alligators. He had many boys die from drowning, getting shot, or getting attacked. He made it across as a survivor so he was a lucky one.