Dumbledores lack of surprise + my point !

[mad_maxime]

No: HPFGUIDX 94053

> > Inge wrote:
> > Dumbledore: "But she (Petunia) took you <snip> 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."
> > Ok - so how DID Dumbledore know anything about Lily's sacrifice at
> > that time? Harry was a little more than a year old and the only
> > person to tell what had happened at his home that night. Not a
> > chance. Alas! Someone else must have been in the house to witness
> > what happened and told Dumbledore that Lily actually gave her life
> > for Harry.<snip>
 
> Carol responded:
> I'm not sure about this, but I think DD still doesn't know exactly
> how Harry survived (it couldn't be the self-sacrifice alone or
> dozens of other people could have been saved from AKs by similar
> sacrifices).
> <snip>

Max responds:
Someone could have been in the house and reported to Dumbledore, but I
think it's more likely that he was able to deduce for himself what
happened.

In CoS (p.317, US Edition):
[Riddle]- "So. Your mother died to save you. Yes, that's a powerful
counter-charm."

In GoF (p.652-653, US Edition):
[Voldemort] - "His mother left upon him the traces of her sacrifice. .
. This is old magic. I should have remembered it, I was foolish to
overlook it. . . but no matter. I can touch him now."

Voldemort might have been "foolish to overlook it", but I don't
believe Dumbledore would be. Just the fact that he used a blood charm
to protect Harry at the Dursleys, as an extension of Lily's
"sacrifice", leads me to believe he was fully aware of how Harry
survived the night.

Just look at it from Dumbledore's perspective.  They arrive at
Godric's Hollow to find Lily and James dead, Voldemort seemingly dead
(was there a body?), and Harry completely unscathed, save for a scar
on the forehead.

I believe Dumbledore knew all about the types of counter charms and
old magic that might explain a situation such as this. So knowing
Lily's skill at charms, I believe he could guess, just from looking at
the situation, that Lily had probably used Voldemort's ignorance of
such matters to her advantage.

Another theory, for which there is no canon evidence, is that Lily
informed Dumbledore *beforehand* of her plan to conjure the old magic
as a last ditch effort to save Harry. It seems completely reasonable
to expect that there would have been *some* conversation between
Dumbledore and the Potters before they went into hiding about the best
ways to protect Harry if Voldemort were ever to find his way to
Godric's Hollow. 

So Dumbledore knowing Lily's plans beforehand seems like a reasonable
possibility to me.