Thank you! I've written a few bond fics (creatur-fics), but it's a plot device I'm wary of using because of all the clichés. In this case, I thought it important they risked it.

Unfortunately, I really can't talk about your guesses because they would answer a definite question about the potion that I don't want answered yet! But yes, it is a big clue.

The secret is revealed in Chapter 12.