This is a page to comment on successful books, and why/how they became so popular.
1. The underdog: Harry is perpetually the underdog, yet ultimately triumphs. His life begins as pathetic, but he is soon whisked away to a fantastic new place where he is important. He is the archetype of most any child's dreams.
2. Little did he know...: Harry's naivete is a driving force behind the plot, and also leads to a sense of tension and danger.
3. Mystery: Rowling only gives us tidbits of information from her vast universe. She shows RESTRAINT, giving one the sense that she has actually thought out a universe that is full of history and detail beyond what is given, and thus she leaves the reader with a sense of mystery, as if they must gather clues to go deeper into the universe.
4. Irony/Humor: the story is written in a highly ironic, almost satirical/whimsical, tone. It is filled with light-hearted as well as dark humor.
5. Lots of character and detail: she creates loads of characters, each with a distinctive personality and purpose, adding depth and complexity to the story. Her universe also contains all kinds of mundane details that are necessary for creating an immersive experience.
6. The villain: every great epic has a memorable villain. I like it when villains are in the background of the story, creating an ominous and foreboding atmosphere.
7. Characters you love to hate: they force you to make an emotional investment without even realizing it. Every action they take invokes a strong response from you, whether it is anger and disgust at something unjust they have done, or a sense of glee when they're thwarted or humiliated.
8. Enlisting the audience as a freedom fighter in the struggle against injustice: making the plight of the main characters in HP relevant to audiences was instrumental in Rowling's success. Morality was often black-and-white, making it all too easy to convince children and young adults to take up arms with Harry. Worthy of note is Rowling's use of modern social dilemmas--including censorship, injustice, and intolerance--to make it very clear whose side is right and whose is wrong.
9. Puzzles and Riddles that need solving: Most of us will think back to Gollum's cave for this one, but this need not be the only example of the rewarding nature of riddle-solving. When bits of the riddle are given over long, intermittent periods, we are in the habit of calling this mystery (see #3). However there can be a near-immediate solution to a riddle/puzzle, in which case there may be yet another in what turns out to be a series of riddles. The entire path to the Sorceror's stone is nothing but a tension-release cycle stemming from a chain of problems requiring intellectual adeptness.
10. Prophecy: Everything happens for a reason, but we are only privy to just enough prophetic knowledge to keep our fascination. No more, no less. Everything else merely seems coincidental. In the far grander scheme of things, the entire Harry Potter series is the slow revelation of the prophecy. The prophecy gives reason for the story to exist. (same with the original digimon!!!)
11. UUMMMMMMMMMm the whole snape killed dumbledore bit, you might think it was a big deal because of the traitor aspect, but i think it was a big deal cuz i didnt actually think he did it, i.e. dumbledore was still alive,