I Knew It: Word of God and World of Thedas Vol. II confirm fan speculation that the Architect is one of the seven Magisters who invaded the Golden City and became the first darkspawn, and that he was once the High Priest of Urthemiel.
Recycled Script: Nathaniel's "Help me find my sister in that big city!" companion quest is similar to Alistair's, except it involves hugs and happy reunions, as opposed to bitterness and accusations.
Shrug of God: The answer to why the player can import a character to Awakening even if s/he chose to sacrifice him/herself at the end of Origins.