Schizoid Character
Not only defenses, but many kinds of structures develop in defensive
ways. Some ego structures actually develop specifically for defense,
for example, those which constitute the schizoid character. In
attempting to avoid dealing with very painful object relations,
the child defends by isolating himself from his felt experience
in general. This defensive detachment isolates him not only from
his emotions, but also from his essential presence, characterized
by vivid affects and qualities of aliveness. If he were in touch
with the essential presence, he would lose his capacity to isolate
himself from his emotions, because the presence would open him
to his present experience, whatever its content. This disconnection
from the essential core makes the schizoid character narcissistic
on some level. (The Point of Existence, pg 187)

The truth is that the sense of separateness of ego is a schizoid
phenomenon, but it is usually experienced in a mild form. The
ego boundaries are a manifestation of the schizoid sector of the
personality, of which no ego is devoid. The schizoid experience
becomes intense and more manifest, and therefore more visible,
when this separateness is challenged. The separateness of ego
individuality is the outward, usually acceptable, manifestation
of ego’s schizoid characteristics. The markedly schizoid
character is basically a personality crystallized around this
sector of the ego. In the process of essential realization, the
issue of ego boundaries is resolved by dealing with the schizoid
sector in one's personality, among other things. It is one of
the most painful to deal with, but not necessarily the most subtle.
(The Pearl Beyond Price, pg 398)