Huckleberry Finn: Growing Up

In Mark Twain's masterpiece, Huckleberry Finn sets out on an adventure that will mark him for life. Two events stand out to me as sure evidence that this is a bildungsroman, that Huck changed and the central story focused on his coming of age. The first is when he decides not to write to the widow and tell her about Jim. He decides he'd rather go to hell than betray the "nigger" who has become his friend. He shows himself more mature than most people around him because he defies social standards and, in his eyes, risks even his own eternal salvation for the sake of someone else. The other scene is when Huck tells Mary Jane about the duke and king's plan. The longer he stayed with those two lying thieves, the longer he prolonged his own maturity. When he finally stood up for what was right, he looked to the interest of the sisters more than to his own interests, which evidences a certain maturity. 

It should be noted that Huck's adventure is not a thrill ride just for the fun of it. That is Tom Sawyer's way, but Huck is simpler at heart and more laid back. His adventure is somewhat unavoidable because of the tough circumstances he found himself in with Pap.  While Huck had to choose to mature through many other decisions throughout the story, he's originally set out because otherwise he would stay in the cabin with his drunkard dad and be beaten and locked in, for who knows how long. It seems almost anyone would have escaped somehow. Yet the decisions down the line show a definite change of character.