Here is the interesting thing, so far as statistical evidence goes, it is suggested that D.I.D could very well be a phenomena that only occurs in places that has been exposed to the idea of D.I.D. With that said there are a few possible reasons to this, one of it suggests the possibility that D.I.D being an actual occurrence is due to some form of classification to explain this mental condition, whereas areas that have not been exposed to it before this might have lacked the classification to do so. However, considering how rare these cases are, I guess we are all left to hypothesize instead.
Now how D.I.D worked for Sybil in the movie is the fragmentation of her being into multiple separate entities in order to face the traumas that she has endured in her childhood. With that said these entities or different personalities will take over the host, in this case Sybil, during a particular event so that the host will not have to endure or face it him or herself. So instead of like how our Merc with a mouth does it where by all of the entities talk and interact with each other and then decides what to do, in Sybil's case however, is she instead completely taken over by her other personalities.
Okay so this raises an interesting question for me, can Deadpool also be considered a person with D.I.D? Both characters share different personalities or entities within a single body but one is able to interact between entities and host while the other is not able to do that until the last part of the movie with the help of a psychiatrist.
So in the movie, Sybil's different personalities are each entities that protect a special part of her. In Deadpool however this is also similar, the yellow box to serve as jokes and the white for seriousness and also his own voice. However during one of the story arches of Deadpool, is an issue in the Deadpool series that kills off these two entities. Leaving Deadpool or Wade with a new box, a red box that tells him to kill everything. I won't go too much into detail as to what happened but I just want to point this out. Those two entities the yellow and white box, served as a guideline for Deadpool to follow, giving him a variation between what he could do and should do. So I guess you could say collectively, the different entities, the yellow box and white box it is what made Deadpool. Similar to D.I.D yet not quite the same with Sybil's conditions. So with that, D.I.D just got a whole lot more interesting.
