In J. R. R. Tolkien's "The Hobbit," Bilbo Baggins and the dwarves escape the wood elves by hiding themselves in empty barrels, which are then released into the river and float the characters away to safety. Bilbo is able to orchestrate the escape by using his ring to become invisible and avoid detection by the elves.
At this point in the story, Bilbo's character has grown from a fairly timid person to a stronger individual who is much braver and willing to take risks for his companions. This character growth stems from his previous successful battles with the spiders, particularly the one that ensnared him while he slept.
When Bilbo names his sword "Sting," he mentally assumes the role of hero and is willing to take risks that he did not before. This is partly due to the fact that Gandalf, whom Bilbo has considered his protector, has vanished, leaving the dwarves and the Hobbit to fend for themselves.
The most important aspect of Bilbo's change into a hero is the fact that, apart from awakening heroic tendencies that already existed inside of him, Bilbo is otherwise unchanged. He does not become arrogant or selfish. Instead, he uses his new abilities for the good of others, eventually leading the character to return to a simple, happy life.