Hi there, welcome to the forum, sorry you are having a rough start of it!
Unfortunately what has happened to you happens to many people who are not given the correct info by who ever they get their bunnies from.
Babies get along wonderfully, then they hit puberty and everything starts going wrong. The lack of litter box habits and the fighting are all related to hitting puberty.
You were correct to separate them! Can you clarify whether they are actually male and female? Or both male? Sorry I’m just confused with the naming!
I’m interpreting this as they are both males? Which is good, so there isn’t a concern of pregnancy.
So, you said you have an appointment for their neuters, which is great, because that is the next step. For now keep them separate, and make sure they can’t nip each other through the bars or get to each other in any way (bunnies are great at finding ways to escape their pens and get at each other).
Once they are neutered, allow them to heal and for their hormones to settle for several weeks (I believe most rescues allow 3), but really you will want to wait until you see the hormonal behaviors die down.
Next you’ll go through the bonding process with them. This first involves pre-bonding (which is living side by side and swapping cages until they seem unfazed by the switching and seem to not be upset by the other rabbit). Since yours fought and are currently acting very aggressively towards each other, you might need a longer pre-bonding period. After that, supervised bonding sessions in neutral territory (a place where neither rabbit has been, ideally not too close to their main areas). This allows them to establish their dominance hierarchy safely. Since you are new to bunnies and bonding, I recommend checking out the bunny info tabs at the top. There is a section on bonding that has the basics (plus lots of other good info on diet, housing, medical care, etc.).
So for now just give Vincent extra cuddles and make sure they absolutely cannot fight anymore.
No more contact or play time together until they are in their bonding sessions after their neuters.
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The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.