Shadows also fascinate me because I often sense that they (and what attaches to them in my perception) are somehow images of lurking subconscious fears. My imagination slips its leash and works a kind of dark magic on the shifting phantoms. Oddly, sometimes, a genuine threat can break the spell.
When I was young (oh, so much younger than today), I would sometimes cycle to see my grandparents on a Friday evening. After a mile or so, the streetlights ran out and I had to rely on the faint light of my bicycle lamp, powered by a dynamo.
On reaching Upton Cross, I tried to freewheel very quietly past the scrap metal merchant's - Mr. Gaskins I think. If I made the slightest sound his dog, which was secured on a running chain, would race towards the source of the intrusion (me) and bark ferociously.
It scared the living daylights out of me (to coin an original phrase) but freed me from the torment of my imagination.