There were times that Sirius really disliked having Remus around, particularly in these family moments - if only for his annoying habit of being a voice of reason. If he wanted someone to be reasonable he would have asked for it, Remus just went and did it of his own accord.
He rolled his eyes at Regulus. "No, I let them see the parts that I want, I'm not an idiot Regulus. What people see of me is what I want to show them, just the way you do - though I happen to have different ideas about what I'm willing to show than you do." This was dissolving into a fight faster than Sirius would have liked, but there were just some reactions he couldn't seem to help.
He was glad for James being there though, and the spoken reminder of what he'd been trying to remind himself mentally of went a long way toward cooling his temper, at least for the moment. "You weren't included in that, you know." He told him quietly, if there was anyone who really knew him it was James after all.
"Look I get it, all of that is part of who you are now, and I know I've done a hell of a job ignoring all of that - but I don't know how to ask you about it without saying something stupid that we'll probably both regret." He sighed. It was hard enough for them without Sirius getting upset all the time learning about some new thing from Regulus' past. Wasn't it enough that he knew he was a Death Eater, that he guessed he'd been responsible for at least a few of the deaths of people he'd known? Did they really have to get further into it than that.
"If being brothers means swapping stories about who we've killed in the past, then let's start. I've got a few stories I can tell you if you really want to know them."