Your mother died to save you. If there is one thing Voldemort cannot understand, it is love. Love as powerful as your mother's for you leaves it's own mark. To have been loved so deeply, even though the person who loved us is gone, will give us some protection forever.
J. K. RowlingSirius looked slightly disconcerted for a moment, then said, "I'll look for him later, I expect I'll find him upstairs crying his eyes out over my mother's old bloomers or something... Of course, he might have crawled into the airing cupboard and died... But I mustn't get my hopes up.
J. K. Rowling