Why didn't Lily have to die?

[rgbmcl]

No: HPFGUIDX 93531

--- In HPforGrownups at yahoogroups.com, "greatelderone" 
<greatelderone at y...> wrote:
> Just out of curiosity, but why needn't Lily have died on the night 
> when Voldemort attacks the Potter residence. Voldemort himself 
> mentions it first in PS/SS and then later in POA we hear him tell 
> Lily to stand aside. Seeing how he killed James, a pureblood though 
a 
> traitor, why does a ruthless Dark Lord actually show an ounce of 
> mercy to Lily who he considers a mudblood according to his ideology 
> and who probably defied him thrice according to the terms of the 
> prophecy. I mean he could just have systemically slaughtered the 
> whole potter family. Why did he actually try and make an effort in 
> having her stand aside? It's so not like him imo.

This isn't really an answer, but we shouldn't forget that LV's mother 
died for him, too (in childbirth, I think (?)).  It's obviously not a 
perfect parallel, because, as far as we know, she wasn't saving wee 
Tom from murder, but maybe in that moment it was something he 
recognized?  I wonder if maybe what we'll be learning more about 
young TR, has something to do with this.