G4 is offering a report of one of Chris Avellone's panels at PAX East which deals with the approach Obsidian took with expanding the scope and content of Fallout: New Vegas with downloadable content. At this point, most of the people who have followed the title should already know most of what Avellone said, but it's still an interesting read. Snippet ahead:
All of the DLC packs and stories also had to be able to exist in isolation from one another. None of them could have any direct references to any other DLC, because players could purchase any combination of them. “If someone doesn't have Dead Money, you can't reference those events in Lonesome Road. It creates a very interesting narrative challenge,” Avellone said.
Having a four hour limit on the narrative arcs turned out to be an advantage by helping Obsidian to focus their themes and stories. The limitation of a smaller voice cast kept the stories tight between three or four main characters. And New Vegas was so huge, Avellone and his team had a lot of content left over, like areas the player couldn't explore in the main game. With these limitations tackled the question became, “What sort of hooks can we include in the main game to hint these DLCs were going to happen?” said Avellone.
Obsidian made sure they dropped a lot of references to Joshua Graham, the fallen Caesar’s Legion commander known as the Burned Man, in New Vegas to set up the Lonely Hearts DLC. They made sure the player knew another courier could have taken the package that was stolen from the player before the game began, but refused the job once they saw the player's name was next on the list. The question of another courier who knew a lot about the player, and who could have set them up to be killed, set the stage for Lonesome Road. And the player's companion from the Brotherhood of Steel, Veronica, mentioned her mentor from the Brotherhood, Father Elijah, who would appear in Dead Money. Obsidian also used visual cues, like pre-war posters for the Sierra Madre hotel and the entertainer Dean Domino in New Vegas to foreshadow Dead Money.