Things like disassociation, splitting and so on tend to be on a continuum. At the end of the day, they are all simply coping mechanisms, and can be used differently and to different degrees in different people and in different situations for the same person.

A major theme in my integration work was owning emotions, thoughts and so on that were very uncomfortable to own as my own. It felt more comfortable to think of them as being "that alter's" thoughts or feelings, not mine. A big hurdle was embracing that every thought, feeling, memory and so on in my mind, was mine.

This was because one major purpose of my alters was in owning thoughts and feelings that were "unacceptable" for me to have as a child, in addition to unbearable feelings and experiences. They didn't just hold onto things that happened to me, but they also held onto things that made me feel ashamed or afraid of what would happen if people knew that I felt that emotion or had that thought.

Because of this, to me it makes sense that a person might split-off parts of themselves that induce feelings of shame or fear. "S" stands out to me in this regard, in particular.