A pendent most often requires one or more of the same as itself to completely function. For example, one playing card requires another against it in order to stand vertically.
Something dependent, further, is an object or unit which is not supportive itself, but requires the support of pendents (together as an independent) to exist in its position (e.g. a spire on a cathedral dome).
An independent unit is one which does not require the specific support of the pendent; It is not dependent. Conceivably, an independent can serve a function similar to a pendent since the independent is capable of supporting a dependent unit, but with or without support from other independents. The pendent, again, is generally useless alone, meaning it is usually dependent, itself, on enough pendents to complete an independent unit.
More so, describing something such as a pendentive.