I have a different take on this particular topic:
I was the scary one in my family. My teenage years were rough, and my parents and I got into a good many screaming matches, as I am sure many other teenagers do from time to time. I was never physical; not by a long shot, but I tended to drive my points home with overwhelming power of will. My family walked on egg shells around me.
That's not to say that every little argument ended up that way, but there were occasions where they would balloon into vocal wars that could last for an hour or more.
I have learned over the years that I have a terrible ability to tear people down. In an argument, I can zero in on a person's fears, insecurities, and often things that they don't even realize about themselves, and I can use them as a weapon and break people down to the point where they simply quit. I have on multiple occasions been able to reduce people I love (and some I don't) into sobbing heaps of sorrow and fear - simply by using my voice. Psychology and decibels were my weapons, and I HATED being able to do that! The worst part is that I could do it without even realizing it, and there have been times where I have. I can also be extremely intimidating through both my voice and body language, and it's something that I am not proud of. It has not served me well.
To an extent, I still can. It has been an ongoing struggle throughout my entire life; the quest to fight fairly in an argument and to keep other peoples' emotions in mind when in a heated argument or when I find myself getting angry.
Fortunately, I have an intense sense of empathy and compassion, and after I would steamroll an individual, I would always feel remorse and concern for them, and I would go to the ends of the earth to try and make things right; especially for family. Needless to say, I have hurt a good many people who have loved me. If I could change it, I would, but sadly I can't. Instead I have had to do the next best thing and learn from my mistakes, make up for them the best I can, and continue forward.
I am married now, and I have a beautiful loving wife that would go to the ends of the earth for me. She knows that I can be an overwhelming force of nature when we argue, but she has also taught me that there is no need to be that overwhelming force anymore, and I am learning to better handle my temper. She guides me, loves me, and she is always patient - even when I am not. I am learning a lot from her, and I can honestly say that I am a better person because of her.
What can you get out of all of this? People can change, and if they don't change completely, they can still learn. Some people just have the ability to be cruel and hateful, and those who don't feel regret, compassion, or empathy are generally the ones you should watch out for and keep a wide berth. However, some people who wish to be guniunely good, like myself, simply have personal battles to fight, and perhaps instead of fearing them, they should be asked why they feel the need to behave the way they do. They are family after all, and if you can see that they sturggle with their anger and cruelty and dislike it as much as you do, then perhaps you should let them know that you love them and help them to better understand themselves. That's what it took for me.