I know I’ve posted a few times recently, but it’s been really great as a first time bunny owner getting to talk to other bunny owners about questions and concerns 
I’ve been reading about bonded pairs and so far my two male holland lops (4 months old, both neutered), Merry and Pippin, are showing no interest in establishing a hierarchy. They’re brothers and have never been separated. They groom each other equally, if one asks for grooming the other one always complies and vice versa. Sometimes they just run up to each other and start grooming the other one unprompted. They eat their pellets out of the same bowl and have never fought over food, they eat out of the bowl together at the same time. They dropped around the same time and they humped each other equally, neither one complained or tried to fight when they were getting humped. They poop, sleep, eat, and play together constantly.
I’m worried that once they reach adulthood, will they start fighting? Is there a particular age they become concerned with dominance?