I'm so glad my reading buddy recommended reading this before Winter!!! 
 SOOOOO many facts have been cleared up. It's also a great refresher on the basics of other characters mentioned in the past, yet, included new information about the Lunar Royals. I loved this story :) 
 Again, I'm sure it's not necessary to read before Winter, but with it only being a little more than 200+ pages and only a 6 hour audiobook, I highly recommend it. The story goes very quickly.