Blood protection (was: Re: CHAPDISC: DH3, The Dursleys Departing)

[Carol]

No: HPFGUIDX 177544

Carol earlier:
> <snip>  The blood protection that *Lily* provided came about because
she had a chance to live but chose to die instead, apparently a 
unique occurrence in the WW until Harry's choice to sacrifice himself
in some ways replicates it. <snip> 
> 
Laura responded:
> So the protection Lily gave was specifically physical?  That is, it
protected Harry's body wherever he was?  Or, to be more accurate, it
would protect Harry's body from LV.  Other agents, such as a 
basilisk, would still be able to kill him, right?   

Carol responds:

Right, or at least, that's how I see it. He's protected from Quirrell,
but Quirrell is possessed by Voldemort and is Voldemort's agent. He's
not, apparently, protected from death by falling, or Snape would not
have needed to save Harry's life by countering Quirrell's curse (with
the unwitting aid of Hermione, who thought she was saving Harry from
Snape) and would not have needed Fawkes' tears to save him from the
Basilisk (itself an agent of Memory!Tom but still fatal, apparently).
The drop of blood in Voldie's veins adds another level of protection,
tying Harry to life while Voldie lives.
> 
Carol earlier:
> > But the blood protection that *Dumbledore* placed on 4 Privet
Drive is different, based on Lily's sacrifice but using her blood 
connection with Petunia to protect Harry. Essentially, Petunia sealed
a magical pact by taking Harry in. As long as Harry can call 4 Privet
Drive home, *there* (and only there) he cannot be harmed. *That's* the
protection that expires when Harry turns seventeen.
> 
Laura:
> So am I right in theorizing that DD essentially blackmailed the 
Dursleys into taking Harry by making Privet Drive a sanctuary (in the
sense of its being a safe place, not a holy one!)?  The first letter
would have said something like "Dear Petunia, your sister has been
murdered by LV, and if you don't want your family to be next,  you'd
better take her child in", right?  Of course, DD would be more 
diplomatic than that, but the threat would be the essential point.
> 
<snip>  
> 
> Yet again, DD decides what's best for people without consulting 
them.  What if he had talked to Petunia himself, rather than leaving a
baby in a basket with a letter?  Petunia might not have had any other
good options, but at least she would have been part of the 
decision-making process, which would leave her with some sense of
control over her life.  

Carol responds:

Poor Dumbledore, being blamed yet again for JKR's plot needs. <smile>
She wanted Harry to be an orphan and a foundling and yet live with his
Muggle relatives as an unloved stepchild, so she had him (or rather,
Hagrid) leave Harry on the doorstep with a note from DD tucked inside
his blankets. We're never told exactly what the note said, only that
DD explained what he had done in the letter he left inside Harry's
blankets (OoP Am. ed. 836), but clearly Petunia did know that Lily and
James had been murdered by Voldemort and that the house (or part of
it) had been blown up and that Voldemort had tried and failed to
murder Harry and that Harry was still in grave danger (either from a
resurrected Voldemort or from his angry followers). Clearly, she
(unlike Vernon) also knew that by taking Harry in, she would activate
a magical protection on the house which would protect her family as
well as Harry (as DD reminds her in OoP with "Petunia, remember my
last." He tells Harry in OoP, "She know that allowing you houseroom
may well have kept you alive for the past fifteen years" (836).

I don't think such a letter necessarily entails blackmail. It would
simply explain the danger to both Harry and the Dursleys (as his
nearest relatives), and Petunia, out of fear of a fate like her
sister's but also, possibly, out of a vestige of the love she once
felt for her sister (or fear of what the neighbors would think if she
didn't take in the baby left on her doorstep) took him in. I see DD's
letter as most likely an explanation and a warning rather than
blackmail, but without the letter itself, it's impossible to say.
Certainly, Harry's safety was DD's primary consideration. Lily's
sacrifice saved Harry at Godric's Hollow, but DD is taking no chances
that her blood will save his life again. He must be kept in a safe
place, hidden from the DEs, until he's of age. That protection expires
either on his seventeenth birthday or when he ceases to call 4 Privet
Drive home, as we see in DH, but the blood protection from his mother
remains in his veins. Voldemort can touch him now, as he couldn't in
SS/PS because of the shared drop of blood, but he can't kill him, at
least not until the scar link is destroyed and Nagini is killed, at
which point both Harry and Voldie are mortal. (It's important for
Harry to *think* he can be killed when he first faces Voldie in DH,
but that's another topic.)
> 
Carol earlier:
> <snip> "The same protection wouldn't come into effect any time a
parent sacrificed him or herself for a child in the WW." Protection
like *Lily's* only came about because she had a choice to live and
chose to die instead. <snip> 
> 
> > Carol, who can find the canon if necessary to clarify the 
distinction between the blood protection placed by DD on Privet Drive
and the original protection provided by Lily's sacrifice, which DD's
spell builds on and extends
> 
> Laura:
> Yes, I'd like to see it.  The distinction raises a lot of questions
for me.  <snip>

Carol again:

Well, I promised to oblige, so here goes. I'm snipping a lot for the
sake of conciseness, so you may want to refer to the passage at full
length instead of my edited version. DD is speaking to Harry after the
battle at the MoM:

"You might ask--and with good reason--why it had to be so. Why could
some Wizarding family not have taken you in? . . . . My answer is that
my priority was to keep you alive. You were in more danger than
perhaps anyone but myself realized. Voldemort had been vanquished hour
before, but his supporters--and many of them are almost as terrible as
he--were still at large, angry, desperate, and violent. And I had to
make my decision too with regard to the years ahead. . . . I was sure
[Voldemort would return], and I was sure too . . . that he would not
rest until he killed you. . . I knew that even my most comples and
powerful protective spells and charms were unlikely to be invincible
if he ever returned to full power.

"But I knew too where Voldemort was weak. And so I made my decision.
You would be protected by an ancient magic . . . which he has always .
. . underestimated. I am speaking, of course, of the fact that your
mother died to save you. She gave you a lingering protection he never
expected, a protection that flows in your veins to this day. I put my
trust, therefore, in your mother's blood. I delivered you to her
sister, her only remaining relative. . . . .

"She may have taken you grudgingly . . . yet still she took you, and
in doing so, she sealed the charm I placed upon you. Your mother's
sacrifice made the bond of blood the strongest shield I could give
you. <snip Harry> While you can still call home the place where your
mother's blood dwells, there you cannot be touched or harmed by
Voldemort. He shed her blood, but it lives on in you and her sister.
Her blood became your refuge. You need return there only once a year,
but as long as you can still call it home, there he cannot hurt you"
(835-36).

Carol, hoping that this quote is sufficient to distinguish between the
protection placed on 4 Privet Drive by DD's protective charm (sealed
by Petunia when she took Harry in) and the blood protection provided
by Lily's sacrifice that saves Harry from Quirrell!mort in SS/PS