Hi Jenn.
I have been bonding my own pair this past month (if you've seen my Penny & Kirby thread that's 5 pages and counting now!), and before that I was on and off bonding a pair of neutered boys which never succeeded.
I know where you're coming from when you want another bunny. Sometimes you just find a great bunny and all you want to do is give it a wonderful home. But consider how it would affect your living situation as well as the living conditions of your own bun. I typically don't advise folks to get a 2nd bun until they've lived with their first bun for 5-6 months. It's an adjustment period, particularly for more difficult bunnies. It's also a good amount of time to make sure you can financially support the bun and kind of understand the full costs of having 1 bun on a fairly regular monthly basis. If you're sure you're ready on that front, there's still more to consider!
Bonding a recently neutered male and an unspayed female will be pretty difficult. Females, as others have said, tend to be more territorial and unspayed females more so. I'm not sure what the personality of Buddy is like other than his cage aggression... is he otherwise a calm and laid back bun? Or is he pretty jumpy all around? It is very important for the buns to meet before you make a decision. You ideally want personalities that complement each other, but a word of warning: what we humans see as the rabbit's personality may not be how the rabbit actually behaves when it is in the presence of another rabbit. That's why bunny dating is so important -- you really want to see how they behave together to see if there's promise to the pair. Spaying the girl would be best, and at a minimum I'd keep them apart another month after she is spayed for the hormones to dissipate. If you try to bond them while the hormones are still raging, they may get a bad first impression and make things all the more difficult down the road.
That said, you do have to prepare for housing and caring for 2 single rabbits for a duration of time. Even the most promising pair of bunnies can take time to bond and they each need their own cage until they are fully bonded. Depends on how big your prospective bunny is, but I usually take a look at the rabbit and make sure that the cage is big enough for the litter box, a place for the bunny to hide and for the bun to lay down length-wise with ease. That's a bare minimum in my opinion. For a bonded pair, my opinion is that the space should be more or less double because they each need to have their own litter box, places to relax and hide away from each other, and a place to sit. Others may have their own guidelines, but I think for a bun to live comfortably even with a companion, they should have their own space to "get away" from their partner. Even the most bonded pairs have their bad days and squabble.
Another thing for you to consider is: how difficult is it for you to handle Buddy? I won't sugar coat this: I had to get *really* good at handling rabbits before I could even attempt to bond my Kirby with any rabbit. He is skittish and really squirmy when I try to pick him up. I used to break a sweat trying to get a hold of his wiggly bunny bum! If Buddy is cage protective, you have to be prepared to get a little beat up because you're going to have to pick him up at least once a day for bonding from his cage to the neutral space. And you have to be able to pick him up or somehow stop him in case a fight breaks out during the bonding sessions. Cage aggression isn't a sign that he won't bond with another bun, but it is a sign that you need to choose a partner carefully, and you have to decide whether YOU can go through bonding him
Not sure how old Buddy is - is he at least a year old? If he is not yet a year old, waiting a while longer could make a difference in his personality. Also, it could take about 1.5 months for a neutered bunny to really work his hormones out, so it is possible you could see him mellow out a little more over the next couple weeks.
I hope that helps!
