I was very recently diagnosed ADHD and I'm honestly still questioning my diagnosis, but my doc has focused quite a bit on relationships and explained the tendency to take things personally or be very sensitive, quick to anger, and emotional in ADHD people. I know this applies to me, and my mom, who my doc recommended getting tested for ADHD like me but who has been previously diagnosed as bi-polar (she's seeing a separate psychiatrist from the one I see and her old one soon I hope!) We have had really bad problems and explosive fights in the past, and a lot of the emotional symptoms of ADHD explain the insane drama between the two of us. Since I've been getting treatment, our relationship has improved a lot

I'm obviously not a professional and very new at this, but I've found support for that conclusion in my hours of researching ADHD. From my experience/reading, it can make you hyper-sensitive to percieved shortcomings, criticisms, etc. It is also related to low self-esteem, poor social skill, and impulsiveness among other things. In my opinion some of these traits combined in certain people can definitely make them predisposed towards being "bullies."

Of course, I think all of these extra symptoms/behavioral patterns have separate and confusing names and may just be comorbidities of ADHD that I don't fully understand, so I'm sure the poster above me is more correct than I am