CREATE TABLE table_17476 ("Series #" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

Who's the writer of the episode see by 12.13 million US viewers?
SELECT "Written by" FROM table_17476 WHERE "U.S. viewers (millions)" = '12.13'
SELECT "Written by" FROM "table_17476" WHERE "U.S. viewers (millions)" = '12.13'