I missed too many days. I'm sorry. Also I mislabeled the day. This should be four. Enjoy.
Emily was using the Solver to assist in baking a cake for Z's birthday. Of course, this had always been associated with a risk of being possessed by Cyn. Well, three guesses for what happened in this story. I mean seriously, who does that?! Baking is sacred!
Either way, Cyn was now in control of Emily's body. She removed the coat and glasses (finding them dumb), but didn't don a bow (she would've if Emily had owned one, but she didn't). She then wasted no time in trying to kill Emily's friends (save for Z, for whom she had special plans). Of course, they didn't go down so easily. And, considering the fact that Z had made a truce with X and Y, this attempt was doomed from the start (I'll tell you about the truce on my introductory to Y).
So, Cyn was evicted from Emily's body. Then Y spent two whole days programming firewalls into Emily's code to keep this from happening again. All's well that ends well, I guess.