When one refers to darkness insidevthemselves they tend to refer to malicious intent, spite, or cruelty they are aware of, a tendency to do or even enjoy doing harm to others, or a willingness to do harm under looser circumstances than others for personal gain.
Very rarely is it such that when one refers to personal darkness that its elemental, primordial, a thing they cant control because it has no name, no pathology, no pattern. Its not a series of actions or behaviors, but it can effect them.
No its far more insidious. Its an intrinsic quality of the self. Its others being afraid of you despite otherwise benign characteristics. Its a subconscious reaction to your actions that assumes malignant intent regardless of altruistic nature of genuinely good natured intention. Its a standard of distrust even your significant others have to tell you they are upset with you until they grow to hate you.
When i tell you i have a darkness in me, this is what i mean. A baleful presence. I am nktjing but kind to my loved ones and friends, yet more often than not unless they too have this baleful presence or a grasp on its nature, even close loved ones can find reasons to break from me. Sometimes its that im doing something mildly inconsiderate that they perceive to be a sign that i dont care about them, when in reality im just oblivious... Or the ever more insidious occurance where my presence in ones life is treated like a dangerous habit, an addiction and they become aware quickly of this and need to quit me cold turkey.
I dont hold it against them, free will exists for a reason after all, no my complaint isnt with others, its that i wish i knew how to cow or control this essence and aim it from my loved ones and only use it to harm or frustrate their and my enemies.
If anyone has any ideas im open to suggestions, magical or otherwise.