Part of the story was completely about sympathy towards molly, how she s grown up, even going as far as to the going "inside" comment and everything else. Part of the book has been to set things going for a harry-molly relationship. As far as murphy harry are concerned, there have been too many betrayals on that front, and Murphy will get darker. In the end however, she ll pick up the sword and see light. We ll see a lot of animosity between Molly and Murphy in the next book, and the whole Harry-Molly-Murphy being cold, and then Harry being the 'winter knight'.. Hence 'Cold days'.

I suppose another part of the interesting story in the next book will be How things shape up between fix and Harry and Lady summer, now that he has finally picked up the mantle of winter knight.I wouldnt put it past fix to run away from Harry

It also means that Murphy will have to get really dark before picking up the sword for the light, and she probably will not do it for a few more books. She may even not do it until the finale trilogy.