Regulus wished that he hadn't come, maybe if he has reached out to one of Sirius' friends, no doubt they had also joined in this coalition with him. Probably would be ten times more pleasant, at least in his eyes it would be. If he were dragged by his toenails to McGonagall it would be ten times more pleasant than having to hear his voice after all these years.
When Sirius was describing what his probable death was going to be like he shrugged. He has thought about it himself, over this past month really. Even if they had magic it was probably going to be nice and torturous. Especially with the information that he had "That's why I plan on leaving, it's not safe."
Regulus just wanted this over with, he would tell them about the horcruxes, and they could believe him or not. Then he would go back to his little encampment that he created, and try his best to survive.