buns are never to old to bond
size age breed, isnt really a factor in 2 neutered buns, age only if one is say 6 months the other 6 years that gap is a bit to big,
people myself included often go by personality
but bare in mind your agressive bun, maybe taken over by what looks like a softie, but kicks your boy into touch, expect the unexpected with bonding, ive only had 2 bonds that have been predictable so far
I have 6 yr old dutch boy with my temprmental dutch girlie whos 3, he spent the first 4 years of his unneutered life,spraying, mounting everything that didnt move, met his now wife all he did was sniff her:lol:, I was very dissapointed as i was so sure hed be the same wit ha real bun as he had been say with my slippers :lol:
as i suggested last night timeing is important, never bond straight after neuter, hormones must settle at least, if you try to bond too soon, accidents can happen, even if seperated the fear and aggession can still be there and ruin it for when to try again, and never ever rush it,
Its like an arranged marriage alot of people think rabbits will hit it off straight away all you are really doing is putting 2 ( or more ) strangers together, they have to get used to each other and that takes days maybe weeks