child abuse
To just state it abruptly, my father was, at a young age, physically kicked out of the house by his step father. Full on out on the street, pulling a red wagon behind him. (This was so traumatic he couldn't handle buying me one, instead buying me a purple one which immediately triggered gender fears.)
@chimerror I forget where I heard this, but one saying comes to mind: "the worst villains are the ones who believe they can do no wrong."