Honestly, I think you need to wait longer to even introduce them. Your new hasn’t even been with you guys a week yet. I think you need to hold off on face-to-face until new bun has had a good month to settle. Most bunnies won’t show they’re true personality until they’ve settled. Your new bun is honestly probably still pretty nervous.

Hi there,

Can you describe your set-up a bit more? As well as the area where you are introducing them?

This might not be an issue, but please be very sure that they cannot nip each other through cage bars. You can use a smaller mesh that they can’t nip through, or have a 4-6″ buffer between the cages/fencing. It is normal for buns to try to do this, even if they are OK in neutral space, but it can set things back and build bad feelings between them.

As far as nips vs. sniffing, you’ll want to watch their body language. Ears back, tail up = aggressive. Ears forward, tail down = curious and interest. Also just how tense they are in general. Rather than completely blocking, I would pet them both when they approach each other so they think they are getting groomed and build a positive association.

It sounds like they are fairly relaxed around each other, so I would go for the petting anytime you aren’t sure, rather than just blocking them. If they seem relaxed you can wait a second or two before you start petting.

Have you pre-bonded (switch living spaces so they can smell each other) yet? Pre-bonding may be the most important step, since rabbits rely most of the sense of smell. I agree with DanaNM, try the petting thing. Doing that saved my bonded pair.