Why do some books seem to get bogged down halfway through, or meander around aimlessly, or simply fail to grab the reader's attention in the first place? There can be a lot of reasons, from poor plotting to a bad narrative structure, or even just because characters didn't wind up as interesting as the author intended them to be. There are a lot of things for an author to keep in mind, but it's come to my attention lately that one huge point of potential derailment isn't even on most writers' radars. That point is whether the story's plot is meant to be driven by characters or by events.
Imagine a book, or a series of books, where the main character(s) go through various adventures, have all kinds of wild things happen, but come out of it fundamentally the same people, reacting to things in the same way, so that you know the issue will be just as much rollicking good fun. That, my dears, is what you call an event-driven story. So far, we've seen them primarily in thrillers, mysteries (Sherlock Holmes is a classic example), and other genres that tend to feature serialized copy about a single protagonist or group of protagonists. As a writing style, it also used to predominate in sci-fi, back in the days of Phillip K. Dick and Asimov and Heinlein's short stories, which were all about exploring how completely interchangeable human beings reacted to the new technologies emerging around them. Truth be told, though, it's easier to maintain an event-driven writing style over a short story than an entire novel.
The alternative is something that's character driven, where the story focuses on the internal struggle of the character; where the main driving force of the plot consists of watching the character's evolution from one state into another. As writers, most of us are more familiar with this style: we put our characters through hell so that they can become beautiful butterflies. And the writing process is all about coming up with new and more inventive ways to do that, and trying to figure out what events would induce the changes that we need and want to see. This style of writing is more prevalent in genres like fantasy.
The real reason that I want to bring these differences up is because although they're something we internalize from reading stories written in the different styles, I don't think most authors are capable of articulating the difference between them very well at all, and that can lead to problems. Especially if an author who is more used to one style tries (knowingly or unknowingly) to write a story in the other style.
This is something the steampunk writing community needs to be aware of. Most of us are coming out of fantasy or sci-fi, both of which are currently quite character-driven genres. But while character-driven steampunk is possible and can be quite good (c.f. Stephen Hunt), the models that we're trying to match, books by authors like Jules Verne and H. Rider Haggard, were almost exclusively events-driven.
Some authors are trying to match that and doing it well. George Mann's Newbury and Hobbes adventures manage to evoke the Holmesian events-driven feel that most London-fog steampunk authors are looking for. Others try to match it, perhaps without realizing what exactly they're doing, and without the knowledge to guide what they're doing, it just falls flat. Much as I hate to pan a book by an otherwise excellent author, I feel as though this is much of what happened with Cherie Priest's Dreadnaught. Her Boneshaker was quite good, but Dreadnaught feels like it can't decide which is more important - the train and the politics surrounding it, or the people riding it. It feels like she's tried to make it a character driven story, and there are some clear attempts at showing Mercy's evolution and growth. The only problem is that Mercy is such a flat and opaque character to begin with that any changes occurring to her seem disjointed and rather random. She grows over the course of the story, but it's in an unpredictable, unfathomable way, and the reader is often left wondering whether the scene that just occurred was meant to be important or not.
Every scene in a book should be important, and every scene should feel important. If you don't know what or who is in the driving seat of your story, though, this gets supremely difficult to pull off. Having multiple foci adds depth to a story when done well, but diffuses and mystifies it when done poorly. Just like sci-fi, I think that steampunk is going to divide (or possibly already has) into hard and soft sub-genres. And like sci-fi, the best hard steampunk will be events-driven, while the best soft will be character driven. Authors need to know what they want to write, and what that means they're getting into before they start. I hope that this brief disquisition will help with that.