So, in the original Desolation, the game was filled with these endoskeletons on the upper floors of the building. In chapter 1: An Act of Destruction, You meet Bonnie and Freddy with these endoskeletons on floor 13 (the mock pizzeria). These two act as a security system to protect Alison from unauthorized personnel accessing the upper floors. On floor 14 (the Arch), you can find multiple inactive endoskeletons throughout the catwalk. One of them has a Freddy mask the first time you enter the area, but lacks legs, has these red coiled hoses connected to it, and has these glowing wires going through its hands, almost like it’s being crucified. Carson’s dialogue here is: “This seems to be the same model I found at floor 13. What kind of ungodly creature did this to it?” The second time Carson enters the area, the room is less illuminated and the crucified endoskeleton’s mask is missing. Carson’s dialogue here is: “A shapeless devil waiting and waiting…… for salvation?” The third time Carson enters the area, the endoskeleton is now spraying blood everywhere. After leaving the area, it plays a cutscene of a rabbit skeleton. Also, floor 14 takes place during chapter 2: Twisted Devotions. After chapter 3: The End of the Beginning, you go to floor 15, where you’ll meet Alison. If you opt not to kill him, a cutscene plays where Alison opens a portal and goes through it. As this scene plays out, blood is covering the screen. You can see an endoskeleton head in the background. My current theory is that the endoskeletons are powered by blood, similar to Torture Suits, but were stationed at multiple locations to entertain guests and possibly collect their blood. At some point, the endoskeletons are called back to the factory so Alison can collect their blood and use it to power the factory, and possibly, the portal.