He smiled, truly happy that she was a Black. Andromeda might have moved away from the family, but some traits seem to survive despite that. "Oh no, I'm pretty sure he has a head for picking up girls, playing pranks, and even creating complex magic to humiliate people. What he can't do is sit still and do research," Regulus said.
"I'm sorry, but I refuse to call family by their last name. Dora, it is, and no matter what Sirius says, my name is Regulus and not whatever absurd abbreviation he can think of at any given moment." That was best said upfront, before Sirius convinced her that it was all right to use a nickname. "Bellatrix is... not fond of what she sees as a stain on the Black name, despite the fact that she no longer uses said name. I'm sure she feels the same about Sirius and both our parents were purebloods. All of that to say that you shouldn't take it personally. It's easier to stay calm when needed, something that Sirius hasn't learned yet."
He offered her his hand. "I guess we can make it official. You do look a lot like Andromeda now that I know. The hair most definitely isn't."
Regulus' smile dropped as she went on. "Death Eaters? Lupin said that the war ended in 81. Why were you fighting Death Eaters?" What in bloody hell had happened? "And I was looking for a particular rare object. I was on my way there when I suddenly showed up here."