Research being as sad as it is has come up with this:
Whether MPD or DID, it is usually the case to have at least one alter that is angry with the core. Alters have suffered through everything. Thier lack of trust and security with the core is usually very strong and has to be worked on.. Alters can act in dangerous behaviors(sexually,drugs, alcohol) and can also revert to SIB(Self Injur. Behav.). Most multiples stem from some for of trauma. It is rare to have multiples w/o trauma.
S.