The Sequel is a strange animal. Once a book or a movie, the latter being more common, is shown to be popular, the creators try to capitalize on that success and fashion a follow-up. But is this a kind of cop-out? Some would argue that the sequel is just a lazy way of doing things, and that the makers simply just try to top whatever they did in the original. Rather than go through the work of trying to find a whole new story, complete with plot and characters, filmmakers and writers just imitate their previous success. On the other hand, it could be argued that the sequel is frequently necessary. After all, how many stories are complete by the end? There are nearly always several ends left loose. With a sequel, there is an opportunity to tie these ends together. So what is the sequel? Mere imitation, or a necessary addition?
Anyone who has ever tried to create a story, whether it be in the form of a book or a movie, knows how hard it can be. The conceptualizing of an intriguing plot. The search for believable characters that readers and viewers will care about. Creating an environment in which these characters live. Striving to make all the pieces fit together cohesively. And then if your story is successful, why on earth would you want to start that whole process over again? Wouldn't it be easier to just use at least a few of the same elements, like the basic characters and the leftovers from the original plot? As they say, "If it ain't broke; don't fix it." And furthermore, if a system works, what reason is there to try to find another way to do things?
But how many times do we decry someone when they attempt to copy the success of another? Christopher Paolini's Eragon for example was often described as a blend of Star Wars, Harry Potter, and Lord of the Rings. As a result, Paolini was often viewed with a kind of disdain. As the series progressed, it became increasingly obvious how little imagination Paolini seemed to have. He appeared to be taking elements from other widely successful stories and blending them together with new names.
Furthermore, sequels are frequently disappointing. Rarely do they capture the true essence of the original, and even more rarely do they do more than simply add more explosions and glass smashing. Iron Man 2 is an excellent example of this. The original Iron Man contained interesting questions about success at the expense of others, with flashy special effects, and frequently witty banter. Iron Man 2 held very few moral queries, instead focusing on bigger and flashier effects, with less witty dialogue. It would seem that sequels don't work, so why do people continually try to make them work?
That said, some sequels are a substantial improvement upon the original. Spider-Man 2 and Toy Story 2 are proof of this. In both movies, much of the more distasteful elements found in the originals were removed, and those elements that did work were improved upon and added to. Christopher Nolan's Dark Knight movies were also successful and excellent sequels. They built upon each other, but didn't focus simply on upping the effects. Why is this? Why are some sequels more successful than others? It would seem that this is due, at least in part, to the fact that the characters change. In each of the movies mentioned in this paragraph, the main characters are found in a new situation, or quickly face a very different foe. New story elements, and moral dilemmas, arise. Iron Man 2 essentially just changed the villain, and threw in a couple new super suits. The Dark Knight introduced the Joker as the new villain, but portrayed him in a whole new light, simultaneously allowing Nolan to raise several very thought provoking moral dilemmas. So while the same characters can be used in a successful sequel, some things must change for the sequel to work.
Finally, there are times when a sequel may be necessary. However, this is usually in stories that are deliberately intended as a single story, but told in three parts. The Lord of the Rings is an example of this, yet The Two Towers cannot really be called a sequel, because Tolkien originally wrote the whole thing as a single book. It could be argued that Nolan's Dark Knight Trilogy fits in this category, since each film builds upon the other, particularly in The Dark Knight Rises, which combines several elements from the two prior films.
Rather than simply conclude this discussion, I would like to invite any and all readers to comment below, expressing their thoughts and views.