I mean, the point of my original Doctor Who example is that you probably could do it pretty easily most of the time. Robin and Kid Flash on a date actually might not reference Batman at all and it would be fine! Robin working a case on his own against one of his own baddies could just focus in on the case! Alfred probably goes and visits a lady friend on the town on his afternoons off and they have a date at a shooting range and he puts Bruce out of mind entirely! Just because someone is the protagonist doesn't mean literally everything revolves around them. But there are some combos of characters where you really can't completely erase a third person from their dynamic, because that dynamic does revolve around the third person.