Parts are sub-personalities that have a certain degree of autonomy from each other and from the Self. They are experienced as inner persons, endowed with beliefs, skills and an emotional life. They express themselves through the body, through thoughts, kinesthetic manifestations (expressions, attitudes, tensions, symptoms), emotions and images. They are endowed with relational capacities, both among themselves and with the Self, enabling them to communicate in a variety of ways, including language. Each of them acts with a positive intention for the system, through the role it assumes. For example, in an adult :

- parent's share,
- the one who exercises a professional skill,
- those who show an aptitude for leisure activities,
- the organizer's share,
- those who enjoy spending time with friends, etc.

It's a state of experiencing. In this state, the individual experiences a certain number of innate qualities, which are expressed through the body: a sensation of alignment, of free breathing; the voice is poised, thinking is clear; there is a sensation of inner space at the thoracic and abdominal levels. From this space, the person has access to a clear perspective, which facilitates decision-making. They see easily adoptable options for getting out of blocked relational situations; they find solutions to their problems. They feel a natural propensity to relate to their own parts, to others and to nature. She accesses a form of compassion experienced as a capacity to resonate with the emotions of others, without being attached to them. She is genuinely curious about others, and is therefore able to approach them without prejudice.

In the event of a traumatic childhood experience, young parts react emotionally and cognitively. If they have the opportunity to encounter - usually through an adult - sufficient compassion (what we'll call here "Self energy in a relational modality"), these emotions and beliefs are somehow regulated, metabolized, so that they don't remain attached to the experience. If they do, they remain "stuck" to the event, constituting what we call the "burden" of the wounded part (or injury), freezing it in the past.
The persistence of the burden of the injured part not only modifies its behavior, but also, negatively, the way it is perceived by the other parts. The psychic system it constitutes tends to become destabilized in relation to the balance it enjoyed before the traumatic experience. As a result, certain parts turn away from their natural role and take on other, "forced" roles, in order to isolate the injured part within the system and from the Self, thus ensuring a new equilibrium. These parts are called "Protectors", and the parts they protect, "Exiles".

Protectors are distinguished according to their protection mode:
- proactive: these are the Managers who want to control the internal and external system, to avoid stimulating the Exile.
- reactive: these are the Firefighters, who want to extinguish the emotional fire triggered by the Exile's stimulation. They want to anaesthetize, cut off feelings, distract and dissociate.

Exiles and Protectors are then engaged in a new psychic configuration that tends to lose its initial flexibility, as its actors are burdened (with their wounds or their protective roles) and are engaged in rigid relationships (either of protection between Protectors and Exiles, or of alliance or confrontation between Protectors).

This system tends to become increasingly rigid, as life experiences provide sources of repetition of the initial trauma. In this new space, there is a primary suffering (that of the Exile) and a secondary suffering nourished by the intervention of the Protectors and the struggle between them. This suffering conditions the symptom, whether psychic or physical.