Werewolves and potions

[Mimi Barker]

No: HPFGUIDX 101039

I've seen several comments in various places wondering about Lupin 
transforming into a werewolf in POA, i.e. why he only transformed 
when he saw the full moon, even though the moon was already full and 
he should have transformed whether he saw it or not. 

I think there is a clue to this in the potion that Snape makes for 
him. When we first see the potion, Snape brings it to him a week 
before the full moon, but mentions that there is more. This tells me 
that it isn't something that he drinks once each month (a week in 
advance), but that he needs to drink it often, at least daily, 
beginning about a week before the full moon. 

So when Lupin forgets his potion on that one night, he has been 
drinking it on schedule up until then, and so it has a partial effect 
on him, protecting him from transformation until he actually sees the 
full moon. 

The drawback to this is that we know the potion doesn't keep him from 
transforming, just keeps him sane once it hapens, so he should still 
have transformed earlier, just not gone berserk. Still, I think it 
matters that he had some of the potion in him, so partial protection. 
Maybe it gave him just enough sanity to run off into the forest away 
from those who would otherwise be his prey.