(Anonymous)
Voldemort's promise to spare Lily: I think the promise was part of a manipulation by Voldemort to send Severus to Dumbledore.
I've a rather insignificant point to add on this, but a point nonetheless, which is Voldemort displays legitimate early intentions to spare Lily (344, US Edition) when he confronts her at Harry's crib. His appeal for her to step aside represented to me his reluctant willingness to honor his promise to Severus. In the end, of course, he was unable to attempt murdering Harry without first offing Lily, yet reading his fleeting reluctance always meant something to me about his relationship with Severus, what that something is remains vague and amorphous.
I've a rather insignificant point to add on this, but a point nonetheless, which is Voldemort displays legitimate early intentions to spare Lily (344, US Edition) when he confronts her at Harry's crib. His appeal for her to step aside represented to me his reluctant willingness to honor his promise to Severus. In the end, of course, he was unable to attempt murdering Harry without first offing Lily, yet reading his fleeting reluctance always meant something to me about his relationship with Severus, what that something is remains vague and amorphous.