the rebirth of the royal legacy

you all know the story of what happened to harry potter, more specifically his parents but what if things went a little differently what if do to sirius black's imprisonment, a curse activated transforming every black woman into slaves to the heir of the house of black, one harry james potter, what happens when he learns his own origins were not as pleasant as people tend to believe and that his parents more specifically his father was much more like severus snapes iteration than what was thought, what if his legacy was greater then any had known even that of the bastard known as james potter himself