Severus' eyebrow went up again. "I would hope that Rodolphus is not certain of that or your life, godson or not, will become forfeit. And those of your wife and son. He has use for you while he think you are his or at least mostly his. Once you are not, you are of no further use and he destroys those who are of no further use."
His eyes narrowed for a moment as he thought. "Then he has some purpose behind showing you that. The question is whether there is any truth in it. Is he exaggerating a genuine problem and if so why? Or is it a complete charade in which case the question is also why? The drinking of the potion in front of you was interesting. Three of the potions of that colour that could be relevant require absolute timing in when they are consumed. A dose cannot be missed. That could explain that occurrence."
He contemplated what he'd seen in the memory regarding Rodolphus' reaction to the news about Montague. "I don't think he knew about it or that he ordered it," he said finally. "If he'd ordered it, he would have been far colder about it and he wouldn't have hesitated to give you the reasons, if for no other reason than because he knows you'd tell Montague what he'd done wrong if he didn't already know. His disinterest..."
He frowned and ran that part through his mind again. "I have only ever seen him like that when he has something else on his mind that is more important to him than anything else. I see two main possibilities in this case. One, he is planning some kind of attack or other such trouble and is attempting a distraction. Or two, he is indeed sick or poisoned, it is more serious than he is letting on and the display he gave you is designed to disguise the true nature of his illness."
He looked down at the memory swirling in the pensieve then he scooped it back into the vial. "Another meeting with him could give an answer but could also make him suspicious if it was not for something worthwhile."