Why did Voldemort die killing Lily?

Why did Voldemort kill Lily Potter instead of stunning her?

My first answer to this question was this: We know from the books that this spell, the killing curse, cannot be blocked. As far as old Voldie knew at the time, any other spell would have a chance to fail if she had magical protection.

The second assumption is that she is an enemy and would definitely be an enemy after he killed her son. Why don't you eliminate an enemy when you have the chance?

The third take was that Avada Kedavra is actually a signature Voldie spell.

The fourth take is what others have already dealt with - he's a bad guy, and he does too.

Regarding the risk of alienating Snape, consider how close to the vest Snape played his cards - he may have asked Voldie to spare Lily, but Voldie underestimated the effect this would have because, like us, he was all know, do not understand The power of love. The only reason he didn't kill her right away is that Snape asked. As for V, he has it tries.

'Well Severus? What message does Lord Voldemort have for me? '

'No - no message - I'm here on my own account ...

"I - I come with a warning - no, a request - please ..."

"What request could a Death Eater make of me?"

"The - the prophecy ... the prediction ... Trelawney ..."

"Ah yes," said Dumbledore. "How much did you give to Lord Voldemort?"

"Everything - everything I've heard!" said Snape. "That's why - that's why - he thinks it means Lily Evans!"

"The prophecy does not apply to a woman," said Dumbledore. "It spoke of a boy who was born at the end of July -"

'You know what I mean! He thinks it means their son, he will chase them - kill them all - '

"If she means so much to you," said Dumbledore, "will Lord Voldemort spare her?" Couldn't you ask for mercy for the mother in exchange for the son? '

"I have - I have asked him -"

As you can see from this exchange, Snape may have asked, but he certainly did not ask - doing so would have shown his hand and made him someone Voldie could see in the future. Judging from Snape's general actions and words in all of the books, especially regarding Voldie, he knew what a monster he was - and he knew he could only push this far without arousing suspicion - and it is likely that he already had his back on the plan to go to Dumbledore to protect Lily, which he could only do if his protest was framed in a way that wasn't "weak". He probably told Voldie that he owed her or that he wanted her as a toy later instead of loving her.