At first, several months ago, I just thought he was charmingly eccentric and a "character".
Over time I noticed disturbing behaviors and acts. He would often sit next to or directly across from college-age women and try to make conversation with them in a flirting kind of way. At first I thought nothing of it. But I started noticing that some of the women were made to feel very uncomfortable and tried to avoid and evade him. About a month or so ago he started cursing under his breath at a woman who would not make eye contact with him. Again, I thought that he was just being "odd".
I think it's important to be tolerant and give people the benefit of the doubt because we can never be sure of what their mental states are or what disabilities they may be suffering from.
On Tuesday, though, things went too far and I spoke up and said something to him! He was loudly verbally harassing a young woman and her male friend because the woman would not stare back at him, I guess... Any way, I saw that the young lady and her friend were getting very upset and didn't know what to do or say, so I turned to the fellow and I said in a calm but forceful tone of voice "You need to stop harassing the other passengers on this bus!" He replied that it was none of my business. In response I said "I am a citizen just like you and everybody else on this bus, and if you don't stop harassing these people I am going to report you!" He mumbled some reply and I told him "Dude, don't push it!" The young lady and her friend seemed thankful for my intervention.
The next day a lady who rides the bus every day at the same time I do (she works at Wendy's at the hospital where I work) talked with me about that guy. I told here that I kond of felt sorry for him because he is obviously mentally ill. She told me that he is more than that, that the fellow is a registered sex offender! She also told me that me saying something to him had encouraged her and a few other regular passengers to file complaints with Regional Transit System about that fellow's behavior.