The Dark Angel
Scorpio deals with the underworld and is associated with the alchemy of base materials. You can see a parallel in base behavior when Scorpio devolves into degeneracy and gives in to lower impulses.
Again from Dion Fortune: "We all know that, when caught off our guard, there comes a dark temptation from the depths of our lower selves, something atavistic stirs, and we think thoughts, or even do deeds, of which we would never have believed ourselves capable. We have heard the voice of the Dark Angel speaking."
A dark side Scorpio lures others into a lair of addiction, sexual obsession, and dark deeds, where their victim starts to feel not quite like his or herself.
Vampires in myth and literature are archetypes of dark side Scorpio. The seductive charm of the Vampire puts the victim into a kind of trance, not expecting the bite that comes later.
A shadow Scorpio (Sun) or someone with strong Pluto or Scorpio elements who doesn't have their own way of refilling the psychic well can become a serial psychic vampire. The evil genius Scorpio knows you better than you know yourself, especially if you're not yet very self-aware.
And as Dion Fortune wrote, again in Psychic Self-Defense, just as fictional vampires like Dracula create other vampires, that's how it is with psychic vampirism.
Fortune writes, “Now vampirism is contagious; the person who is vampirized, being depleted of vitality, is a psychic vacuum, himself absorbing from anyone he comes across in order to refill his depleted resources of vitality.”
Scorpio has to do with the shared energy field, especially between two intimate friends or lovers. One subtle phenomenon is the taking on of another person's psychic detritus.
This Scorpio experience associated with subtle energies is difficult to detail and prove. It requires the strengthening of energetic boundaries, as well as detoxing the dark energies dumped into your field.
In this way, a dark side Scorpio can serve as a teacher, forcing us to exert will and save ourselves from attack. This means going to the root of the soul's ability to know sovereignty, tracking what hooks us back to their source.
Once you've recovered from this kind of psychic attack or bondage, you have Scorpiocity of the best kind. It's the knowing that you cannot be hooked or controlled by those that would seek your weak spot in the psyche or soul.