Sirius had the incredibly strong urge to take the heavy torch in his hand and throw it at the back of his brother's head. Regulus was being an idiot. No matter what he did, he would end up dead and it seemed to Sirius that he might have wanted it that way. There was nobody in that hospital that wasn't wanted dead by Voldemort and his followers. Regulus was just being an ass.
"Turn left and go upstairs," he said shortly, waving the light in that direction. He knew better than to do anything before Regulus had the chance to tell whatever news he had come with. He wasn't going to ruin the Order's chance at having some kind of advantage, whatever it was, but Sirius wasn't going to make it easy for Regulus to leave and he'd take him the longest, most convoluted way to McGonagall he could manage.