I’m betting the new buns had some bad experiences with the 2-year-old and that is why the first family gave him back. If so, he is probably scared to death. My first buns was mishandled by two families with children before me, so she was really scared and mean. Some things I did to win her love:
1. Don’t force it! Wait. Wait. Wait.
2. I put a day’s old sock that I had worn in her cage, so that she learned my scent wasn’t mean and wouldn’t hurt her.
3. I never forced her out– so if she hid in the back of the cage, I let her be. Sometimes, I would just sit with the cage door open and talk soothingly to her. Sometimes she never came out. Eventually she did.
That buns of mine ended up being the friendliest thing to me. We even slept together in my bed! (She was potty trained, of course!) The key is to be patient. The poor thing probably had it rough. A 2-year-old doesn’t know how to properly handle a rabbit and, likely, neither does a parent who gets a 2-year-old a pet rabbit.