One of my buns hasn't gotten neutered yet because of health problems, not contagious.  The other one, a female, has been spayed.  She seems to completely hate the male and she even lashes out at him between the bars of the cage if I don't watch her.  I keep their cages right next to each other and there's no aggression that way.  They grew up together and started fighting around maturity.  I've tried bonding a few times, but they just automatically go for each other the moment they see each other free.  Is it safe to try bonding when they are this aggressive to each other?  If so, how can I keep it safe if spray bottles don't work?