Regulus was arguing with himself about what he had done. This was Sirius, and he wasn't the most calm of individuals, but Regulus didn't have friends. He didn't have anyone but Severus and Remus and now, he couldn't talk to either one of them, which left his brother. He was mentally playing out possible scenarios when the knock on the door arrived.
He went to the door and it let Sirius inside. "Thank you for coming," he said in greeting. "How are you and James?" Oh look, he could do proper talk with his brother now. "Would you like something to drink?" A bottle of whiskey seemed like a very good idea right now, and he went to the cupboard and opened a bottle. "There's tea if you'd rather, but you might prefer Odgen's."