"Nothing wrong with thinking, or even over-thinking, sometimes," Severus answered with a shrug, putting the vial away. "There isn't a great deal else to do here, after all." He turned to face her then, leaning against the desk, though a safe distance away from the cauldron. That way he would know when it started to boil, but he wasn't close enough to get burned.
"The faux disappearance was a little over a month ago," he continued. "One of our captors posted something to the network saying they had made a mistake and some of us would be returned home. Then a few people disappeared, only to be returned a few days later, with no memory of having gone."
He smiled when Mercy asked if the potion changed colors. "A few times, actually," he replied, nodding. "It will start out, ah, caterpillar colored. Then, once I add the mustard seeds, it will turn a bright orange, and finally, it will end up a reflective light silver. Almost like mercury, though a shade or two brighter."