Why Lily could have saved herself

[Goddlefrood]

No: HPFGUIDX 152333

This theory really falls somewhere between the history of magic and 
the future of the books.

I am firmly of the view that JKR would not have placed as much 
emphasis as she has on Lily's gifts as a potioneer unless they were 
to play an important role in book 7.

It is a part of the history of the wizarding world that Lily is 
deceased, but it has also been declared, by Voldemort himself, that 
Lily needn't have died.

There is a plausible explanation for this, which runs something like 
this:

Harry discovers that the reason Lily might have been spared was that 
she had discovered some powerful potion that no one (apart from 
perhaps Snape) is aware of and which has qualities that would finish 
off the evil that men do or strip a wizard of his powers perhaps.

Only she was capable of making it thus explaining why Voldemort was 
prepared to spare her life, but she refused to co-operate, as we 
know, and was, therefore, killed.

The secret potion then went with her to her grave.

Any other plausible explanations out there?

Goddlefrood