Echo?

OK So what the heck is the deal with Mr. Echo!!! What was the point of his character? What plot point was revelaed or lesson learned from his story? Prior to his death he still didn't even make peace with his brother? And then that stupid black fog that makes ratcheting, clanking sounds threw him around and killed him and his last words are "You're next." Boooooooo! You just know the explanation for the fog in the end is gonna stink too. J J Abrams you're loosing me. I believe the next episode is the Fall Season finale too! In the first week of November! Boooooo! Somebody save me. Make sense of some of this...