In the Extended Cut, it is revealed that Commander Shepard was resurrected with the use of vorcha gene therapy. On the Citadel, Shepard removes her/his fleshy mask, revealing the vorcha within and goes into a bloodrage, destroying all three terminals so the Starchild can’t force you to make another pointless decision.
The Reapers die out of shame from the realization that they were following a blob of energy shaped like a tiny white boy for millions of years. Everyone flies off back to their homeworlds in the warm glow of the titanic eezo explosions. The End.