when describing his brother, sirius will always explain that regulus talks a lot. he always has opinions or stories. he likes to talk about his day, things he saw, anywhere from bugs and rocks to things he accidentally eavesdropped on (sometimes ppl forget he's in the room).
even before regulus arrives at hogwarts, a year or two later, all of gryffindor and sirius' friends outside of gryffindor know, that regulus black likes to chat
however, when regulus black arrives at hogwarts the most he says is a polite 'fine, and you?' when someone asks how he is, other than when responding to professors. even his greetings tend to be just nods.
sirius, however, maintains that regulus is SUPER chatty. and actually just the other day he was telling him about how snyde is is cheating on his gf, who's craggy's sister which has led them---as in snyde and craggy the brother---to have fight in the common room
but again throughout hogwarts, regulus maintains his quiet persona so ppl have no clue wtf he's talking about
other than remus of course, who once was in the hospital wing when regulus was as well (minor quidditch incident) and when sirius came to visit them, regulus excitedly told him, in detail, about this one quidditch move he'd been wanting to do, his practice of it, how avery said he couldn't, and how he managed this really difficult move, despite getting hurt; and did sirius know the move was invented in 1807 by a french player? and it then became a signature move for that team for years to come, until of course, another french player invented a different move which took over, not to say the first one died out, but became less popular---
and of course, peter, who once decided to head off towards the kitchen for a snack and walked in just as regulus was in the middle of explaining about how mulciber was getting high secretly, but was using muggle methods, and was too ashamed to let anyone know---as they used magical ways to get high---but his secrecy led for avery to assume he's seeing someone which really bugged him for some reason, so he tried to convince snape to help him figure it out, but snape was busy, so he accused snape of knowing and covering for him, and now all the boys are fighting about it. and regulus is not part of the drama but he was bored about it so he paid a younger student to tell their friends loudly that personally, they supported snape and mulciber's romance, and that made the fighting even worse but now regulus is growing bored and tired of the drama and loud fighting. how bothersome.
and james who has seen regulus letters to sirius before he came and during when they stopped talking in public and theyre always very very long starting off with how he's been and how everything is, and did sirius know that the pronunciation of this one charm has changed over the centuries but still works with seemingly equal effect and isnt that so curious and isnt sirius so curious about how language and magic work together and speaking of, there's this new candy at honeydukes that regulus really wants to try and that barty has been teasing him about his sweet tooth but its not his fault sweets taste good and speaking of which could regulus borrow that one quill sirius has, the one with the deep blue feather?
]of course there is also barty who likes to ask regulus here and there about anything interesting happening and gets long lectures of how the relationship between water and magic just isn't studied enough and how space, water, matter all change magic and how it works and isnt that so fascinating barty? speaking of which, regulus really wants there to be a racing team at hogwarts, so many of the other schools have one and they wouldnt even need anything special but brooms, which the school has, not good ones sure, but still. and anyone who wants to race, would obviously buy their own like with quidditch.
and pandora who oftentimes just exists in silence with regulus but sometimes, late in the evening, the sun setting, a shared early dinner between them, regulus will talk about everything and nothing at all. ]
