When did Draco Imperius Rosmerta?/Seeds of Betrayal/LiD!Snape rides again

[houyhnhnm102]

No: HPFGUIDX 149801

Pippin:

> It could be someone with access to Rosmerta and 
> access to the school. Interesting that JKR's website 
> tells us that Lupin was (or was supposed to be) stationed 
> in Hogsmeade.

houyhnhnm:

Lupin is a murky figure to me.  I have to admit that whether I believe
he is ESE or a Good Man Who Does Nothing depends on whose post I have
read last. I lean towards the latter.  In fact it's hard for me to see
Lupin as an out-and-out coldblooded ESE, but I can imagine him as
someone whose moral cowardice could extend as far as allowing himself
to be used as a traitor, while abhoring the results of his treason.  

I have been thinking of the question of who helped Draco at the same
time that Lupin's anguished cry upon learning of DD's death has been
playing in the back of my mind.  

"'No!'  Lupin looked wildly ... Lupin collapsed into a chair beside
Bill's bed, his hands over his face."  And just in case we don't get
the significance "Harry had never seen Lupin lose control before; he
felt as though he were intruding upon something private, indecent."

When I read the passage the first time I was still in shock after the
events on the tower. It didn't make much of an impression on me.  It
was only when reading the quote again on the list a few weeks (?) ago,
that it struck me in a new way.  

It is exactly the response I would have expected from Lupin in PoA,
had Sirius actually been a traitor, lured Harry to the Shrieking Shack
and killed him.  It stikes me as the lament of someone who saw it
coming and either did nothing to stop it or was half unwillingly
helping things along.  Remorse, such as Snape felt when he realized
that his own actions would end up bringing about the death of Lily (if
you believe that--and I do.)

Did Lupin see it coming--the assault on Hogwarts--and either failed to
act for whatever reason Lupin habitually fails to act, or did not
consider what the loss of Dumbledore would mean to him?  

Draco boasted of his connections with Fenrir Greyback at the beginning
of HBP, so when the DEs showed up at Hogwarts with Greyback, I took it
for granted that he was one of the "better people" helping Draco. 
Possibly directed by Narcissa since Draco calls Greyback a "family
friend".  Either Narcissa or Greyback could have then enlisted other
DEs.  Any one of them could have imperioused Rosmerta, it seems to me.
 Draco could have been summoned and threatened by Voldemort during the
Christmas break.  He's still pretty cocky up until then, even though
he has already failed with the necklace. 

But clearly, whoever imperioused Rosmerta, however Draco was
communicating with the Dark Order while at Hogwarts, Greyback was
involved in the plot.  And Lupin's job was to act as a spy among the
werewolves.

Could there have been a scene (unseen) which was a mirror image of the
one with Snape at Spinner's End.  One in which Lupin got a whiff from
his werewolf contacts that something was up, but whereas Snape went
too far to obtain information (some think), Lupin failed to follow up
on it at all.  Or was he actively involved?  LIH, LIHOP, or MIHOP?

Whatever the answer, I am convinced that Lupin knew something about
the impending attack against Hogwarts and failed to share it with the
Order, and that his anguished cry of "No!" bespoke remorse as well as
grief over Dumbledore's death.