Hi! I had that problem with my two step-sons. The youngest got lots of attention...and needed it, as his Bio-mom is....well....currently on probation for drug related issues. He was taken from her at 4yrs old and I've been with him since he was 5. He's 11 now.
The oldest one's mom is still in the picture, and has gotten better in the mom area, but he used to feel that we "babied" my youngest and he didn't think it was fair. (the oldest is 16 now, btw and has lived with us since he was 12.) He's kinda stand-offish too, but we found things that just he and my husband could do together that he liked, or things that just he and I could do together that he likes. I even went as far as to ask him if he minded if I hug him! They're so weird as adolescents and they act like they don't want it, but they need affection too. Sometimes I get a real hug, other times I just "bump into him" in the kitchen, or playfully punch his arm, you know, rowdy boy stuff. Sometimes I just ruffle his hair which ticks him off b/c he doesn't want it "messed up", but he always smiles afterward.
I guess I really don't have any solid advice, but thought I'd share my family's experience...