This definition includes three components in SPs: anger/aggression, unidentifiable nature, passing appearance in critical situations. Let me elaborate rather in detail on these three components,
It is often unclear who a SP is mad at when it exhibits its anger and frustration. When a SP shows anger, it tends to direct it in a rather indiscriminate way. it might yell at, or lunge toward whoever is around. It might attack whoever seems to incriminate the host personality, obviously in his/her protection. However, it might hurt the body of the host, or even try to kill him/her, which automatically kill itself. Some SP, when asked why he engages in self-destructive behaviors which simultaneously endanger SP itself, states "I don't really care. I'm totally OK if I die. Or I don't even know if I'm alive or not".
Difficulty in being identifiedOne of the reasons why SPs sometimes do not seem to own their clear identification is because they are not fully formed as a personality; they are not altogether crystallized in their character formation. Often they are in a trans-like state or somnambulism, in a clouded consciousness, without a capacity to identify him/herself or even respond to a question. When a SP is in a fugue state, they would wonder without purpose or destination. However, there are other cases where SPs simply do not want to be seen or understood. Some SP send his clinician a blunt message, such as "leave her alone" or " don't mess with us", or "don't even try to get hold of me", expressing their deep distrust and clear wish to alienate the clinician. It appears that some states of SP require a lot of mental energy and they literally cannot "stay up" for a long time after they use up their energy and tend to be gone rather quickly.