Came in expecting motivation episode. Did not expect motivation to come from kicking the heroine at the worst possible moment.
Once I realized it was Nui (slightly surprised), I also realized how the plot handled Mako was really smooth: She got Mako caught by the Discipline Committee and sent to battle. Convenient way to shuffle Mako into the next areas Ryoko will be appearing, and it also got her out of the way when Nui revealed herself to Ryoko.
What I can't get a read on is Satsuki and Ryoko's "relationship". While she did steal the scraps of Senketsu to use for her army, she didn't have to save Ryoko's life to do that. This raises the "frenemy" flag...but I can't help but feel there's more to it than that.