This is the Ra term for a soul of 4th through 6th density who decides to incarnate in third density for a specific mission.
This generally fits with the idea of coming from the future into the past in order to affect some change or open some new possible outcome. This is discussed in many places in the Cassiopaea material. The concept of a sort of feedback loop or resonance between pasts and futures is quite central to the Cassiopaea material. The wanderer idea is one form of this, sending messages from the future to one's past self is another form of the general theme. If we see futures and pasts as if co-arising from a plane beyond time, one may even think that the future sends itself to the past in order to create itself. In order to avoid paradoxes, one cannot carry certain information in reliable form from the future to the past. Therefore the wanderer forgets the world of origin, except as a vague recollection and messages from the future self cannot be authenticated or validated with certainty, as is the case with channeling.
This gives room for infinitely many possible timelines and space for free will at each point. It may be that those timelines with the greatest internal consistency are the most 'real,' so actions at any given point are not indifferent on the grounds that all possible combinations happen in some parallel scenario. Internal consistency would here come from following a certain internal nature or soul disposition - the manifestation is different but the principle the same throughout the densities.
The idea of wanderer is not limited to a future self sending itself to the past but this is the angle most explored in the QFS context.
RA: I am Ra. As we have said before, Wanderers become completely the creature of third density in mind/body complex. There is just as much chance of such influence [inspiration by 4D STS] to a Wanderer entity as to a mind/body/spirit complex of this planetary sphere. The only difference occurs in the spirit complex which, if it wishes, has an armor of light, if you will, which enables it to recognize more clearly that which is not as it would appropriately be desired by the mind/body/spirit complex. This is not more than bias and cannot be called an understanding. Furthermore, the Wanderer is, in its own mind/body/spirit, less distorted toward the, shall we say, deviousness of third density positive/negative confusions. Thus, it often does not recognize as easily as a more negative individual the negative nature of thoughts or beings. [?]
QUESTIONER: If a Wanderer should be successfully infringed upon, shall I say, by the Orion group, what would happen to this Wanderer when harvest came? RA: I am Ra. If the Wanderer entity demonstrated through action a negative orientation towards other-selves it would be as we have said before, caught into the planetary vibration and, when harvested, possibly repeat again the master cycle of third density as a planetary entity. [End quote]
Mostly discussion of wanderers is centered around service to others missions but the concept is not limited to this. Very little of this matter may be known with certainty. Ra claims that up to 1 percent of the 1980's human population would consist of wanderers, of whom about a third were conscious of being wanderers. The claim cannot be substantiated but seems to be at least broadly exaggerated if we are to think that such people would become participants in the time's esoteric work.
The concept of an advanced soul making a sacrifice by taking human incarnation for the edification of humanity is nearly universal in spiritual traditions, thus the concept has abundant parallels. Boddhisatva would be a related Buddhist term.