Apparently he would be right to be cautious about the potion. This is a tragedy, after all. Jean Baguette continues onward, becloaked, and Grantaire steps away and changes back to the old woman... and suddenly stands straighter and laughs, sinister. "Ah, that fool boy. Little does he know that I'm a wicked sorceress in disguise! And in recompense for a slight his grandfather did to me oh many years ago, he will die on yonder mountain!" Another, even more sinister laugh, before a quick return to our ill-fated protagonist, still walking in circles around the tables, only they're clearly intended to be steps up a steep incline.