CREATE TABLE table_22380270_1 (written_by VARCHAR2, us_viewers__millions_ VARCHAR2)

Who was the writer for the episode with 2.15 million u.s.viewers?
SELECT written_by FROM table_22380270_1 WHERE us_viewers__millions_ = "2.15"
SELECT "written_by" FROM "table_22380270_1" WHERE "2.15" = "us_viewers__millions_"