The toughest part of parenting a RAD child for me is the lack of reciprocity. A child with RAD cannot give back to their caregiver. They give absolutely nothing back and take everything. My daughter has no concept of family. Yes, we have rages, lying, stealing, manipulation, etc. But the lack of love and the lack of even understanding basic love and respect is the most difficult for me.
This is also the most difficult thing for my wife and I. We just want to to be loved back. It's hard.
If you want behaviors, here are some of the worst (sometimes typical) behaviors we have experienced:
Defecating on a siblings bed, smearing poop on walls, trying to strangle kittens, constant false accusations of abuse from siblings, hugging strangers, and peeing pants at every Holiday. Holidays and birthdays are always a treat. At least one of our 3 RAD kids will ensure it will be a disaster somehow. These we can deal with, it's just behavior. The lack of any caring feelings to us as parents hurts.
It does take a certain type of person to choose to live with, care for and love these children. With a lot of therapy and structure they might be able to love you back.
Over the past 2 years, 2 of our children w/RAD are improving greatly. One is not, she needs control so much and she rarely gets it. Her whole life is consumed with manipulation to gain that control.