What turned Snape (Was: JKR site update SPOILERS)

[justcarol67]

No: HPFGUIDX 159026

Allen wrote: 
> Instead of turned or playing a complicated role, another option is
> that Snape was maneuvered into some type of magical obligation that
> forces certain actions.
> 
> Consider the following:
> 1) Snape had a life-debt to James
> 2) Snape overheard part of the first prophesy and reported this to
> Voldemort.
> 3) Voldemort killed Lilly and James as part of his response to the
> prophecy.
> 
> Thus, Snape played a direct and significant part in causing the
death of a person to which he owed a life-debt.
> 
> While there is much that we do not know about life-debts and how
they work, it seems that playing a part in causing the death of person
owed a life-debt is very likely to have serious side effects.  One
possible side effect to being magically forced to avenge the death in
some fashion.  It is thus possible that Snape is magically bound to
somehow see that justice is obtained for James.
> 
> A magical obligation imposed on Snape against his will could also
> explain a number items.  Dumbledore's trust in Snape could be due to
> the knowledge the Snape is magically forced to work towards
Voldemorts destruction by the obligation.  Snape's sorrow over Lilly
and Jame's deaths can likewise be explained by Snape realizing that he
must now take a long-term course of action that he might otherwise
wished to avoid, followed by years of bitterness at being bound to
this new path in life.  All in all, a magical obligation would have
the power to create a resentful and conflicted character that is
unable to do what he really wishes but must instead dedicate his life
to avenging one of the people he hated most.

Carol responds:
But Snape "returned to our side" before Godric's Hollow and was spying
for Dumbledore "at great personal risk" before he was hired as Potions
 Master several months before the Potters died (probably in July or
August of that year; he would have begun teaching September 1.) So the
life debt doesn't explain why he turned against Voldemort or why
Dumbledore trusts him. All it explains is why he would regret James's
death and try to save Harry in Book 1. It doesn't explain all the
other attempts to save Harry's life, or the spying at great risk to
his life, or the loyalty to Dumbledore. I'm not arguing for LOLLIPOPS
here. I think that the idea that Voldemort would go after a baby and
his family, people that young Snape knew even though he didn't like
James, may have been sufficient to make him turn to Dumbledore and the
spying certainly contributed to Dumbledore's trust in him--though I
see no reason why Dumbledore would not divulge that to Harry. Maybe
there's a connection with Regulus Black, or maybe young Snape did
something to contribute to Harry's protection on the night he was
found in the ruins of Godric's Hollow. (I can see him at least
examining the baby to determine that he wasn't possessed, for example.)

But Dumbledore values choice and IMO he would not trust Snape because
Snape was under some compulsion. He somehow knows (or believes, if you
don't accept DDM!Snape) that Snape, of his own free will, has chosen
to be loyal to Dumbledore rather than Voldemort, to serve the leader
of the Light side rather than the leader of the Dark side (though he
must still seem to do so). Consider Snape's words to Quirrell about
"where your loyalties lie," which imply strongly that Snape's, unlike
Quirrell's, lie with Dumbledore. Also "If you are ready, if you are
prepared" implies that Snape has been working for a long time, partly
on his own and partly with Dumbledore, to prepare for the dreaded
confrontation with Voldemort. He isn't being compelled to do so. He's
choosing to serve Dumbledore--and that's one more reason why
Dumbledore trusts him and values him (note his prolonged silence after
Snape goes off into danger in GoF), as he would not trust and value
someone who was compelled into false loyalty.

There is no indication in the books (unless we count Snape's
half-truths to Bellatrix in "Spinner's End," which we can easily show
to be incomplete and slanted to make him appear loyal or provide
acceptable excuses) that Snape is loyal to Voldemort. It's possible
that he's out for himself, but most likely Dumbledore had some real
and valid reason to trust him *completely* and to know that Snape's
loyalties lay with him.

Carol, who thinks that Snape's loyalty to Dumbledore is personal and
therefore more intense than the loyalty of someone who had always
opposed Dark magic (like, say, James Potter or Sirius Black), who
fought for the Order rather than for Dumbledore himself