This is a normal human ability. A result of paying attention, whether consciously or not. Back in the old days of sailing ships, a skilled sea captain could tell you who was the captain of a ship when only the sails were visible over the horizon, so you couldn’t see the hull of the ship or who was on deck even with a telescope. Source: my dad who was a sailor. Tram and train drivers can also tell just from watching video of one stopping and starting who the driver is. I suspect the abuse/PTSD has developed your ability way beyond the level the rest of us have. In a way it’s a superpower, and something to cherish I think. Like the ‘nose’ of a professional perfumier or wine maker.