User blog comment:Fraidy-Cat/Fixing ME3's Ending in Three Changes/@comment-1440333-20140323205149/@comment-1440333-20140323210922

Thats what the War Assets that allowed you to unlock Synthesis do. But at the same time Synthesis is not an option a paragon player might pick, ditto Destroy or Control for a Renegade player. The endings are the ultimate grey area in the game, with each having merits and sacrifice to make them the best selection. Forcing a player into a default ending based on their past choices is impossible, as how a character might view something like dealing with Saren or the genophage might not reflect how they want to deal with the Reapers and the galaxy as a whole.