Let me start by saying I think step-parents have a difficult job to begin with. It doesn't matter how old the child is when the step-parent enters their life, there is always that underlying "you're not my mommy/daddy". I was one at one time, and I remember that chasm always being there (I have recently been in touch with my former step-daughter and am pleased to report she has grown into a fine young woman and is pretty awesome in her own right). Being the step-parent to a RAD brings it's own challenges.
I remember the first time my wife of 12 years met my RAD. She was 3 years old then (my daughter, not my wife!) and she hid behind my leg when I introduced them. I thought it was cute at the time, but it seems to have been an indicator of things to come. My wife has always been great with kids. She works with them and has always been able to reach them on their level, especially the younger ones. Not so with my RAD. RAD wanted nothing to do with her. It wasn't so much that she wasn't her mommy, but I now know it was more of a fear of getting close. After all, when one mommy ignores and neglects you before abandoning you (it didn't really happen quite like that, but in her head it did), why would you want another one? Why set yourself up for MORE pain? So their relationship was rocky from the start. When I would go to work, my wife would read to her, sing to her and try to play games with her, but all RAD wanted to do was go to pre-school. She didn't want the closeness.
I can't imagine how hard that must be for a person. I, at least, have some attachment with my RAD since I've been there for her since day 1 (well, ok.. since day 90 something since I was in the Navy and across the country for the first 3 months of her life), but no matter how hard my wife has tried, RAD has never let her in. Oh there are moments, glimpses if you will, of caring and a desire to be close expressed by RAD, but nothing that ever seems to stick. Yet my wife has stuck it out for over 13 years - never giving up, never giving in. But their relationship is strained. Wife feels rejected (which sucks even for non-RADs) and RAD takes that as "well I must not be good enough for you to keep trying", not really seeing that after 13 years of rejection, ANY person would have trouble giving it 100% all the time. But she does her best and I love her for it.
So if you're a step-parent, give your son or daughter a hug today. Keep trying - these kids really DO want to be loved (ALL kids, not just RADs), and there is no greater gift you can give them. You can teach them about sex, you can teach them how to drive, but when it all comes down to it in the end, what they will remember is the love you gave them.
So go and give your child a hug. Today.