Hmm, do you have a friend who would allow you to take Dorian over and try neutral territory there? Or could you just not allow him in your room so that could be neutral? Sorry if this isn’t a satisfying answer. <3

I have had good luck bonding rabbits using an x-pen.  Even if the pen is in a room that  one of the rabbits has been in before, it can become its own little neutral space.  You can place a sheet, blanket or large towels on the floor to mask any scents already on it.  You could even hang some blankets on the side of the x-pen to take away the sight of known furniture or items in the room, although I have never done that.  My husband and I get inside the x-pen with the rabbits, just in case there is any fighting (which we’ve never had) or any excessive humping (also never had).  We start with about 10  minutes the first day and increase the time each day, until we can see that the bunnies are fine together.

I think a combo of what tobyluv suggests, and maybe designating a room now that he is no longer allowed in might be a good idea. Give enough time, that room should become mostly neutral eventually.

Kitchens and bathrooms can work well because the floor can be wiped down to neutralize smells easily (and cleaning up is easier!).

Bathtubs are also popular when neutral space is at a premium!

Louie was free roam before he started bed peeing 🙄 and my plan was to have a two-layer xpen situation, an xpen for the bun and then a second one surrounding it to provide a little bit of buffer space.

X-pens or other temporary housing are usually necessary for bonding. I like to make mini-NIC cube condos for during bonding, then I can reconfigure them into one larger one once everyone is bonded. Dorian will probably be grumpy about it, but it’s only temporary! You also might end up with a new bunny that is not as ideal for free-roam, or everyone’s litter box habits can go out the window temporarily, so it’s good to have enclosures for both buns in case you need to pen them sometimes.

You can either give each bun alternate roam time while the other is penned, or divide up the space so they can roam at the same time. You’ll just want to use a doubled up x-pen to make the barrier, so there is a buffer of space in between to prevent nose nipping.

And yes, you actually want the new bun to be able to roam in his territory (as long as Dorian isn’t in it at the time!). With pre-bonding, you typically swap sides to accomplish this, so the buns kind of lose track of who’s territory is who’s.