I've had many experiences and have posted some of them in related areas in other discussions. I never doubt when someone says they "see or hear" things, or when unexplainable events occur.
We live within certain dimensions, and we sometimes catch a glimpse of another. Likewise, those beings or energy forces, existing in their dimension, come through to ours. There is so much energy associated with the life force and that energy continues on and on. When a human being dies, the soul can linger around before departing into it's next experience. Usually the soul seeks the comfort of the familiar "human" and wants to be there; but many times I believe the "stranded soul" lingers outside and stays instead in familiar places, buildings, objects, etc. Eventually, that energy is transferred, otherwise the soul does not complete it's mission towards perfection. Perhaps there is some truth in a "stranded soul" needing a guide (of sorts) to get them back on track.
And, yes, there is also always the opposite of the light, the good, and that is the dark side. We should always try to work toward good in our life, so that the dark and the bad that resides there, will not find a place to dwell in or around us. Good and evil exist side by side, but one who choses good, will progressly move forward. If lessons are not learned, we are doomed to live them again and again. Souls are not perfect and they can become damaged along the way. In their journey towards total perfection they can become infected with desires that are opposite those designed by the universal creators. Damaged souls infect the humans they dwell in. I believe there is such a thing as an evil soul, possibly damaged beyond redemption. This is the sinning soul that will eventually die an everlasting death. Humans are the objects which the souls live and travel in; they have a genuiene love for their host. Striving to live in tune with one's soul is something that we should work towards, as we will have good benefits.
But for those infested with a totally evil soul, they are beyond saving. These are hateful humans that will never fit into society. They think and behave differently, and have no conscience.
Just some of my own opinions here.