So I'm going to discuss some of the structures Blizzard has in place to work with their external authors as well as my personal creative process. Please note that this is only the way I have experienced things, and Blizzard's longer-standing authors such as Richard Knaak or Christie Golden may have a very different routine.
Working with Blizzard
In my experience, an outside author really does not have any control over what stories get told. Once upon a time Blizzard did ask me to pitch them some ideas, but ended up scrapping them in favor of the leader stories project. I am really not in a position to suggest I write something for them. If they want me for a project, they'll contact me and ask if I'm interested.
Once I have verbally accepted an offer, contracts are mailed and signed, and I head off to Irvine for a meeting with the Blizzard Publishing team, which is the primary point of contact for authors working on expanded universe content.
The Blizzard folks present their vision for the story and we have some discussions about what kind of characters and scenarios to involve. Blizzard usually has a pretty clear idea of the themes they want explored in any given piece of writing, so my job largely comes down to how best to execute those themes within the parameters I've been given.
After enough details have been hammered out to the satisfaction of all parties, I head home and get started on the actual writing. From here, the project has a few distinct stages:
Outlining First I create a solid outline based on the notes and ideas discussed at the meeting. The outline gets sent to Blizzard for review, we discuss things like characters, flow, and locations. Once they're happy with it, I proceed to:
Drafting This is the part where I have to actually write the darn thing. It often involves late nights, alcohol consumption, coffee, swearing, pacing, the wanton destruction of innocent paper products, and eventually, typing. After the draft is complete, it goes to:
Blizzard revision Whoever is supervising the project gives the draft a read-over at this point. For Heart of War that was primarily James Waugh, for the Quest for Pandaria series it was Micky Neilson. We go over things like voice, pacing, and structure. They let me know what things aren't working and give me suggestions for how to fix them, or if to get rid of them completely. We usually go back and forth a few times, and once they're happy, the draft goes on to:
Lore review In which the lore team goes over everything with a fine-toothed comb for the sake of internal consistency and to catch all my glaring lore omissions, errors, and sins. I almost always manage to give some random minor character the same name as a major NPC, and that has to be fixed. The lore people are good, folks. Seriously good. Once they're happy we proceed to:
Copyedit 1 Cate Gary is the Publishing team copyeditor, and man, is she good. I've been known to sit at my desk hyperventilating at the red comment boxes on the side of the screen, thinking to myself, "CLEARLY I'M INCOMPETENT QUICK GET ME A DITCH INTO WHICH I CAN THROW MYSELF" ...okay that's an exaggeration. But ask me about the time I had to ask her what an antecedent was, that was a heaping helping of humble pie.
Copyedit 2 I've usually forgotten something or screwed something else up in making the edits from copyedit 1, so we go through the process again.
Copyedit 3+ As many times as it takes, folks.
Once I get an all-clear from copyedit then my part in the story-creation life cycle is complete. From there Blizzard gets it set up for the web, assembles any illustrations or screenshots that might be going with it, and I'm sure all sorts of other stuff about which I remain blissfully ignorant. Sometimes months can pass between the point when I've completed a piece and when it appears on the website. Such is the nature of publishing!
Creativity in a Sandbox
The other half of my licensed fiction equation is the actual writing process itself. When I get a Blizzard project, I have specific parameters for its setting, the main characters involved, and the reason the story is being told. Beyond that, it's generally left up to me to figure out how best to achieve the story's purpose. For Heart of War, the purpose was to flesh out Garrosh's character and better understand his perspective. For Quest for Pandaria, the purpose was to show how the mists were lifted from Pandaria and set the groundwork for the themes that would be important to the Mists xpac--family, home, and the cost to both that war extracts.
With Blizzard material my cardinal rule is to never forget that the story is not mine. Anything I write can be tossed out, for any reason Blizzard wants. Blizzard does, truly, want authors to be able to maintain their own voices in the licensed work. Nonetheless, it's typical for something I really found compelling to end up on the chopping block, usually either because it contradicts established lore (or unreleased lore I'm not aware of), or because it solidifies a detail that Blizzard doesn't necessarily want defined yet. If you go back and read the original version of In the Shadow of the Sun and compare it with the official version, you'll notice a lot of specific details removed, and that was the main reason why.
Good outlining often lets me find out which of my ideas are a no-go before I invest effort into writing a scene that's destined to be cut. It's also important for complex story lines, such as in part four of Quest for Pandaria, which had a fairly intricate construction. For a short story, there were a large number of characters to track, which meant some extra attention to detail.
Speaking of characters, I often have the option of either creating original supporting characters for a Blizzard story, or integrating existing ones somehow to fill a needed role. I prefer to use established lore figures or NPCs when possible, both because, as mentioned earlier, unique names are in short supply, and because I figure readers are more likely to emotionally invest in writing that features people they already know. Incorporating Krenna and Gorgonna in Heart of War was a deliberate choice for this reason. Any orcs could have had that conversation with Garrosh, but using characters that many players were already familiar with allowed me to add a layer to that interaction that would have been otherwise difficult to achieve. I love little touches like that in writing that I consume, so I make an effort to put it into what I create.
Ultimately, writing licensed fiction with Blizzard is an extremely collaborative undertaking. Somehow, their ideas and my ideas have to combine into something we can all be pleased with, that does what we need it to do, and that (hopefully!) can provide some compelling narrative to fans and players who might be looking for a way to enjoy Azeroth outside of the game itself. As a relatively inexperienced writer, the process has taught me a lot and I certainly hope to continue to learn, as well as produce some fun reading for other WoW fans like myself. It is both an honor and a privilege!