I do wonder whether this is aggression and/or a rabbit who enjoys chewing and nipping clothes/fabric. One of my rabbits loves digging and chewing into people’s clothes, and she is in no way aggressive. What can be nice about chewing clothes that a human is currently wearing is that there is inherent resistance and it’s sort of stuck in place, and for many rabbits, they tend to chew/dig at things that don’t move around willy nilly, like a small chew toy or blanket on the floor.

In general,  I would highly recommend not letting the rabbit be with your two year old cousin. Both the rabbit and the two year old are prone to doing things that will make the other unhappy…

You want to provide feedback that biting clothes is not allowed. This does not mean punishing the rabbit, as they don’t understand that, but you can gently use the back of your hand (to protect yourself from nips) to move the rabbit’s nose away from your clothes if she is starting. That’s what I did with my Fable, who has left a many holes in…. almost all my pajama bottoms within the first month of me learning how to communicate with her about it.

Also, if she is a fabric chewer (again, not an aggression-based behavior, just a preference for letting out energy!), providing 100% cotton blankets, towels, or fleece blankets (do not give if she eats them) can be a good way to redirect that energy. You can also just have a cardboard tube or something nearby to hold in front of her to redirect that chew energy so perhaps she can pick up that she can chew cardboard or something else if she is feeling bored.

Lastly, nipping is a form of communication for rabbits. If a rabbit bites you, you usually know because it will draw blood. My Fable has only “bit” me once and my thumb bled, but it was because I was holding a hay mat for her to chew and I wasn’t paying attention. So in all the times she’s nipped me, while it is a painful pinch, I know she’s not actually trying to hurt me — she’s just trying to say “move” or “pet me” or express something else.

I just wanted to add that you can “squeal” if the bunny is biting you. Even if she isn’t actually biting through your clothes, you can still communicate with her by letting out a high pitched squeal. This tells her that she is hurting you (even if she’s not) and will prompt her to adjust her bite.