I like these guys a lot.  As you can see here, I had the basic image down from the start – feathery serpentine thing.  I had a lot of trouble with their heads though, and you can see several different designs in the corner there, including a horrific hammerhead sort of rendition.

This one wasn’t dated, but judging from the nearby pictures it was done sometime around June or July of 2011, very soon after I first started working on D.E.I.T.Y.  Their design has remained essentially unchanged this whole time.