When Will You Rest? {FNAF & KNY Crossover}

Information

I'm sorry everyone! I thought of this one day, could not let it go, was upset that it wasn't a thing yet, decided to make it into a thing by writing a story because I can't draw.

...

Yes, I have problems. We have all acknowledged this by now.

But in all honesty, I love FNAF, but the franchise has been all over the place. I mean, what is the timeline? Hello, someone explain all of the random moments in the franchise that don't make sense.

The character of Cassidy, however, is one of my favorites and she's my favorite of the Missing Children. The thought of a vengeful soul following William around to make sure he gets justice served to him is interesting.

Also, do note that Yoriichi is going to be a female in this book. It just makes most sense for me to write... I also hope it avoids me being offensive. The name will still be the same though.

Before you all ask the question of why Muzan and Yoriichi as the "reincarnations", I'll tell you. Think about it:
W-I-L-L-I-A-M -> M-U-Z-A-N
C-A-S-S-I-D-Y -> Y-O-R-I-I-C-H-I
Both have the same first letter of their first names as the last letter of their previous names... Okay, maybe that one is an Easter egg.

Mostly.

There are a couple of other reasons though that make sense.

First, Muzan creates new demons to essentially kill people and do his deeds, with the Demon Slayers having to pick up the mess caused by the demons. William is similar with the animatronics as he created them to kill, specifically the Funtimes. Both seem to be scared of someone or something: William by Cassidy (in my opinion, it could not be true) and Muzan by Yoriichi.

On the other hand, Cassidy seems to be willing to do anything to get William to serve justice. From the springlock suit to Ultimate Custom Night, Cassidy wants William to atone for his sins and helped force him into the springlock suit. This is also because in this story, Cassidy and William were close before William killed Cassidy. Yoriichi is kind of similar by the way he attacked Muzan since he was the demon king and Kokushibou for turning into a demon (she saw it as betrayal in this story, not just because she kind of had to as a Demon Slayer).

Also, two other important things for the story. One, Cassidy and her twin Andrew (from the books, also Cassidy is younger than Andrew, but she died before he did) came from a neglectful household, much like Yoriichi and Michikatsu do in Demon Slayer. That was one of the reasons why Cassidy got so close to William prior to her death. Also note that Cassidy thinks that Andrew hated her. He does and doesn't at the same time. Second, Cassidy, unlike the rest of the Missing Children minus Charlie, knew who killed them all. How? Well, when William was killing Cassidy, he took the Spring Bonnie mask off. This was to show Cassidy who he was and show that he never cared about her, unlike what she thought. Cassidy doesn't trust adults now, which is why she... or Yoriichi... doesn't talk much in her new life.

There will be a lot of fluffy and angsty Yoriichi and Kokushibou moments. Yoriichi will still be strong, but there will be abilities brought in with the aspect of Cassidy being a vengeful soul. Kokushibou will still be a demon but the two will be closer than in canon. Also, Cassidy/Yoriichi is going to die shortly after Kokushibou turns into a demon by William/Muzan in the same way he killed her before.

Her soul will take the form of either a 7-year-old (since that is how old Cassidy was when she died in my AU) or a seventeen-year-old. She can also take the form of either when she was alive as Cassidy, her soul form, her alive child form when she lived as Yoriichi, her teenager form from Yoriichi, or her dead form (aka her fallen angel/demon form because Cassidy is a fallen angel bordering demon in my AU and if she ever does have the opportunity, she would go to hell. She, unlike William, accepts that because of her actions and takes full responsiblity. Also, her dead form is a mix of Cassidy and Yoriichi, since she finally moves on).