Potions Professor Snape had been at odds with Potter since they were students. By extension, he hated Potter's son, but when the boy was attacked, he chose to rescue him. After all, he is also her son.
One obvious bug is that Snape is not a pureblood, but I didn't know that at the time of writing. After all, this article was actually written very early. I don't want to change it now. Let it be. But I can't remember why I thought Snape liked Lily.
Conception: