Whatever happened to the Prince’s potions book? (was: Request for new topics)

[Neri]

No: HPFGUIDX 152394

What happened to Prince's potions book since Harry had hidden it in
the RoR, and where is it now? The answer seems obvious to me – Draco
has it.

Here is what we are told about the place in the RoR where Harry hides
the book:

***************************************************
HBP Ch. 24 pp. 526-527 (Scholastic):
Harry hurried forward into one of the many alleyways between all this
hidden treasure. He turned right past an enormous stuffed troll, ran
on a short way, took a left at the broken Vanishing Cabinet in which
Montague had got lost the previous year, finally pausing beside a
large cupboard that seemed to have had acid thrown at its blistered
surface. He opened one of the cupboard's creaking doors: It had
already been used as a hiding place for something in a cage that had
long since died; its skeleton had five legs. He stuffed the Half-Blood
Princes book behind the cage and slammed the door. He paused for a
moment, his heart thumping horribly, gazing around at all the clutter.
. . . Would he be able to find this spot again amidst all this junk?
Seizing the chipped bust of an ugly old warlock from on top of a
nearby crate, he stood it on top of the cupboard where the book was
now hidden, perched a dusty old wig and a tarnished tiara on the
statues head to make it more distinctive, then sprinted back through
the alleyways of hidden junk as fast as he could go, back to the door,
back out onto the corridor, where he slammed the door behind him, and
it turned at once back into stone.
***************************************************


The skeleton in the cage is probably the Hand of Glory. Why else would
it have five "legs"? Draco must have hidden it there, near the
Vanishing Cabinet he was working on, in preparation for his final
operation, and also because this would be by far the best hiding place
at Hogwarts for such a Dark object. Of course, he would easily deduce
from the number of artifacts around that other students (and teachers)
know about the RoR and use it, so he had to disguise the Hand as
something more innocent – put it in a cage and it looks like the
skeleton of a little animal. Harry hidden the book right behind the
cage, and he marked the cupboard in a way that Draco couldn't have
missed. He must have found the book. Maybe it wasn't a coincidence
that soon after it Draco succeeded in fixing the Cabinet he couldn't
fix for almost a year. Could the book also have a Fixem-sempra spell
in it?

Harry never came back for the book, although he wanted to:

***************************************************
HBP Ch. 24 p. 530:
"Are you telling me," said Hermione, "that you're going to go back — ?" 
"And get the book? Yeah, I am," said Harry forcefully.
***************************************************

...but it was too dangerous:

***************************************************
HBP Ch. 25 p. 537:
He had not dared to return to the Room of Requirement to retrieve his
book, and his performance in Potions was suffering accordingly (though
Slughorn, who approved of Ginny, had jocularly attributed this to
Harry being lovesick). But Harry was sure that Snape had not yet given
up hope of laying hands on the Prince's book, and was determined to
leave it where it was while Snape remained on the lookout.
***************************************************

After Dumbledore's death, the Trio talks about the book (p.638) but
there's no mentioning of going back to get it, so Harry wouldn't find
out that Draco took it. 

What did Draco do with it? It doesn't look like he was carrying it on
the tower or during the flight, but he had several hours since he had
managed to fix the Vanishing Cabinet until the operation started. He
could have easily gone to Borgin & Burks. Maybe he even called the DEs
from there. He'd know that, whether the operation succeeded or not,
he'd probably won't be able to stay at Hogwarts after it, so he'd take
with him to B&B any valuable possessions he didn't want to leave
behind. And the book was right there in the RoR, why not take it too?

Draco would probably conclude that it was Harry who had hidden the
book there (maybe only the sixth year NEWT class use these textbooks –
 that would certainly limit the number of suspects) especially if he
finds the Sectumsempra spell. And he would immediately conclude that
this was the secret behind Harry's success in potions. Would he also
figure out that it was Snape's? And if so, which of Snape's schooldays
secret are in there that Draco might find interesting?

Neri