It might help to cite the example of my own buns as ones that will require some work to bond with. I’m just starting the process of properly bonding with Panda and Fernando myself. At this early stage, they’re still wary of me, particularly Panda; Fernando was quite affectionate at our first couple of meetings but has been more reserved since moving in with me, in large part, I think, due to the big change in living circumstances. From what I know about Panda’s life before she was rescued by Friends of Rabbits, she appears to have come to her previous owner(s) from a breeder, and from my conversation with their foster mother on the subject, I guess – though I’ll probably never know for sure – that they gave her up to the shelter when they found out she was pregnant, which indicates the breeder didn’t keep good control over their rabbits. So she probably wasn’t at her first home very long before going to the shelter, where she had her kits. Their foster mom told me that when she was rescued, Panda was, at first, quite frightened of people, and it took several months to get her to the point where she could start trusting them again. The kits have been in a much better environment their whole life, so they’re naturally friendlier.
So my plan is to spend at least some time with them every evening while they’re out playing in their X-pen. I have to strike a balance between being too importunate in offering pets and too distant from them, but the thing to do is basically to sit there, let them come to you on their own terms, talk to them and acknowledge their presence. Essentially, let them warm up to you in their own good time until they start coming up to you and asking to be petted (they usually do this by snuggling next to you and putting their heads down, which is a request for grooming in bunny body language, they may also nudge you with their noses to get your attention).