Where a place doesn’t arise from nature it can arise from spiritual principle, though it is a rare thing.
What about those who don’t have guides to bring them back to the people? Generally one of two things happened. They would become lost and start behaving in ways that people would describe as demon possessed, or they would find it in themselves to fight off much of the influence they gathered and find some sort of center, though still not returning to humanity.
Is that sort of case common or rare? It’s more rare than not, but common enough to occur steadily. For every socially acceptable group of shamans there would be one who entered this last state I described instead. They would try to be careful about selecting apprentices because they wanted to avoid this loss.
Could it not leave them at risk for an actual demon possession? It depends on what you mean by demon possession. No soul is ever fully lost, but some can get seriously disoriented, wind up being an angry beings mouth piece.
Like an entity invading or stealing your body? One that is more powerful than you can cope with? People did and sometimes still do become over powered. Self-knowledge is a must.
So learning spiritual self defense? Yes, developing spiritual strength, flexing those spiritual muscles and learning how to put them to actual use.
In voodoo, most people either wind up becoming les serveteurs, ritual dancers, or houngans or mambos. The houngans and mambos are thought to serve a spirit they call “the master of the head.” It’s a spirit that seems to influence them most strongly, but they are able to remain grounded in communal life and the values of their people. The serveteurs, also known as “horses”, come under the influence of spirits only during their ceremonies, and otherwise show no sign of spirit possession in their day to day lives. But less frequently someone experiences a shift in relationship to their loa that is described as “serving the loa with both hands”, meaning none offered to humanity.
Like any great super hero, I suppose their bat or spider is their spirit? It is more their leader. They have their own spirit, but the loa act as intermediaries between humans and the divine.
Your thoughts are welcome. Be well friends.