Benevolent makes me think kind schizophrenic robotic overlords; benign makes me think comatose vegetable schizophrenics whose subconscious is more active than their mind. Either would make a good story.
Truth continues to be stranger than fiction, humanodon: http://www.tulpa.info
I have heard the word "tulpa" before, but always described as an imaginary friend that one convinces oneself is real. I have heard of something similar, where someone who has amnesia will sometimes display a distinctly different personality than their pre-amnesiac persona, or even people who have suffered some sort of mental or physical trauma and for some reason they then begin to speak in a different accent. I know it's unethical to experiment on the human mind (and I would not advocate such a thing), but I do wonder if subjecting ourselves to certain stresses with the intent of adapting the mind in desired ways might be possible.
Is it unethical if one is doing so oneself? From what I understand people are taking the development of these personality fragments into their own hands (and at their own risk). I supposed it touches on the same field of pros and cons are the arguments for and against experimentation with entheogens / hallucinogens.