BioWare has hidden data for a new Mass Effect 3 DLC pack within the files of the game's new 1.85GB Extended Cut.
The revealing new expansion is set to focus on a traitorous Reaper named Leviathan.
A partial script, spotted by the BioWare Social Network, has been extracted and posted to Pastebin. It includes fresh dialogue from all the game's main characters (presumably recorded alongside the Extended Cut).
Shepard is sent to rescue the scientist Ann Brynson, who you find at a Reaper-indoctrinated mining facility. The colony has been controlled by a Reaper named Leviathan for 10 years.
Leviathan is referred to as a defector, a traitor who killed one of its own kind.
One dialogue line hints to more information about the Reapers' creators, briefly alluded to by the Star Child in the game's ending.
"So the Reapers did not fully exterminate their creators. That suggests they are fallible, even on large or long-term scales."
Leviathan can then join the fight against the other Reapers, presumably becoming a War Asset. Brynson can either live or die based upon your choices.
A Reaper named Leviathan has been mentioned before in Mass Effect lore. Scanning a planet in Mass Effect 1 revealed "The Leviathan of Dis", the corpse of a presumed-dead living starship. Then, in Mass Effect 3, the character Balak (if kept alive in Mass Effect 1 DLC Bring Down the Sky) hints that the Leviathan was an dormant Reaper, which the batarians have accidentally reactivated.
Mass Effect 3 producer Mike Gamble last night teased via his Twitter that information on more content was coming: "As I've said before, we do this for you! EC was our gift to the fans. Hope you enjoyed. Also... keep your ears open over the next little while." BioWare is scheduled to address fans at the San Diego Comic-Con (July 12-15th).