They knew the player was a courier, often delivered dangerous packages, and had traveled out west into the Mojave desert. Obsidian wondered what would have happened had the Courier delivered their package rather than being shot and having it stolen before the game began. That single, successful delivery would have completely changed the scope and layout of the entire Mojave Wasteland. Avellone and his team wondered about all the other side quests in New Vegas, and what if even a small percentage of them had the same world-shattering impact? That's when the team began to get excited about the four DLC packs.