where his civilizations, including our own

I don't really see Snape's insistence on the potion as him needling Lupin about his dependence on it (and him). It's more like he's afraid of him and absolutely doesn't want to take any chances. I must also point out that what some people say about how Snape should have taken a goblet of potion along when he went to find Remus seems to be contradicted in this scene since he says Remus is to take it right away. It probably needs some time before it would work properly.

And is it just me or does "I was just showing Harry my Grindylow,' " sound extremely suggestive?

And "Fascinating"? Hee! He's quite the Vulcan!