Can passive aggressive people change their ways?

Yes through counseling and sometimes even meds. I was diagnosed with Bipolar disorder at 19, and through therapy, Wellbutrin, and Seroquel is was able to change my ways. The major problem lies within the person, and there willingness to admit to their problems and seek treatment. A side note: If the person has a chemical dependency issue, (smokes pot everyday, drinks), its a sure sign they may need some sort of medicine, therapy, exercise, better diet, etc. And lastly, I have heard from experts that behavioral modificatin after 30 years old is very tough. So if you have a loved one who needs help, I would defiantely recommend a counselor and/or therapist ASAP