I grew up with a "Jekyll & Hyde" father who was wonderful most of the time, but when he'd get mad he'd explode in a screaming, pounding-his-fist rage. It was never directed at me, I was the golden child, but I watched his temperament change like a light-switch as he'd yell at my mother and brother. He'd pound his fists on the kitchen table when he'd get mad, yelling to get his way and we would cower and walk on eggshells trying not to upset him.
After my parents retired, my mother had a heart attack and he took care of her for 11 years, refusing all help, despite my constant efforts to hire caregivers whom he would throw out. When my mother nearly died from an infection caused by her own waste because he had not kept her clean and hadn't taken her to the doctor, I had to step in despite his loud protests.
I started to experience his rages at a heightened level over things that seemed so illogical and irrational. When he took two filthy hand towels out of the trash and threw them at me, accusing me of throwing out all their things, I was stunned and sobbed my heart out to have him turn on me. I thought it was just more of his bad behavior of a lifetime, getting intensified by my mother's near-death illness and by the stress of caring for her for so long without help. I assumed his rages occurred just because he had always had a bad temper, was so stubborn, hated change, and was furious with me for interfering and trying to help him.