Daddy and Mommy have become such common ways to refer to a Dom completely disconnected from any "taboo" roleplay (they're still used there of course but very common with people who don't engage with that sort of thing at all) I wonder why brother and sister haven't caught on more, especially as the age gap of most dynamics is probably a lot closer to that than mommy/daddy (which I know doesn't really matter but it might to some).

I for one really like to be called big brother and I have had plenty of subs who liked doing it. But I am also into roleplaying an actual sibling relationship so I guess I'm not an "objective" person to give the input.

And to head this off before people say it: I am perfectly fine doing it myself even if others don't. It doesn't matter what other people do as long as I enjoy my dynamics. But I am genuinely curious