"The smile was because you used it to describe me," Remus chuckled. "I slipped a short while ago and called myself the 'serious Marauder' in front of James, earning the pun."
Remus was a long way from truly understanding the world the Black brothers came from, he thought. But then, there was also James to consider. James had an irrational hatred for all things Dark Arts. It was part of what he used to excuse what they did to Severus in school. And they were both, Remus and Regulus, aware of how much ahead of everything Sirius put Potters. "I sometimes think it's a requirement to ask the hat to put you in Gryffindor or you don't get put there. You have to want it to get it."
There were many things Remus might just be figuring out. But, the likelihood of a Black being as innocent as that smile pretended wasn't one of them. "Of course you don't," he teased. "I can see I'll have to explain it to you later.
"We have to stop bringing up these long stories when we really don't have time, or are in the wrong place," he said with a tiny shake of his head, lowering his voice because this was not something he wished to broadcast to the staff at large. "Essentially, I had my eyes opened that night. My friends and I had treated my condition like a game. But, that night I almost killed someone. I didn't feel I could trust my best friends with my secret any longer. I couldn't see how I could ever trust someone with it enough to get close to them and I was clearly too dangerous in general."
And when Sirius had tried to apologise the first few times, he'd yelled almost those same words at him. Of course, then there'd been a war and then his experiences after. It had just never seemed like a good idea.