Griffin and Schroeder and are now a bonded pair (both neutered males).  I has tried introducing them before but had humping and scuffles.  They have been in a huge x-pen with a divider down the middle for about 10 months or so- and there were no fights thru the bars.  I would often catch Griffin sticking his nose thru the gaps trying to get Schroeder to groom him.

I re-injured my back at the end of August and the bunnies have not been out for playtime like they have been- since I cannot bend over to pick them up,  Hubby was mainly caring for bunnies- cleaning cages, etc.  I was doing better- went to pet Griffin and he had lost weight!  He has been eating all his pellets and greens- it is hard to say how much hay as we just throw handfuls in.  I think he was spending too much time with his nose thru the bars since he was lonely.  So I removed the divider- and they are best buds now.

It is pretty adorable- Griffins ear often ends up over Schroeder when they are next to each other!

So it technically took a long time- but they decided for themselves that they wanted to live together.  And Griffin no longer jumps out of the 4 foot x-pen.