Severus arched an eyebrow when Theo mentioned Montague and then nodded once. "He mentioned it," he said briefly.
He eyed the vial curiously then turned towards the covered pensieve that sat on the far bench. "Wait," he said as he stalked over and removed the stone cover. He levitated a series of flasks over to the bench and carefully moved the memories from the pensieve to the flasks. The silvery memories swirled inside the flasks and Severus sent them carefully over to the locked ingredient cupboard and stored them in there for now.
He then held out one hand for the vial. He emptied it into the pensieve then lowered his face into it. He watched the memory played out, his eyes narrowing as he saw the state of Rodolphus' arm as well as his general behaviour. He couldn't identify the potion that Rodolphus drank and there were at least a dozen that he knew of that were that colour.
"Interesting," he said calmly when he withdrew from the memory. "He tends towards impatience when he's sick or injured. He doesn't like it when his body can't keep up with his mind. It's unusual for him to show such weakness to outsiders but then it's a matter of how much he considers you to be an outsider. Obviously I can't tell you much about the potion solely based on the colour but there are potions of that colour that are used to treat some of the symptoms of blood poisoning and a few other types of poisoning. If I were to make a judgement based solely on that memory, I would suspect some sort of infection. They can be insidious if left untreated for a while and would explain the behaviour he exhibited."
He arched an eyebrow again. "Of course, it could easily have been an elaborate charade though for what purpose is the more interesting question. Not to mention why he would bother with such a display with you. He would only do so if he suspected your loyalty was not entirely with him and you would therefore be reporting to someone else." He gave Theo a sardonic look. "Does he have reason to suspect your loyalties?"