It can morph itself to look exactly like you, and speak like you. In the process, it will understand all of your simplest weaknesses, and your most powerful faults of what makes you, you. It will attempt to throw you into despair to doubt yourself.
Could you stand up to something that could unravel and point out your deepest flaws?
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I would think that most people would be apathetic or react with anger to their annoying clone than be reduced to a weeping husk.