Snape heaved out a gusty breath, as if trying to rid himself of his former irritation. When he spoke, his voice was soft. "Nor do I enjoy having more than a decade of unpleasant experience dismissed out of hand. Especially when all I was trying to do just now, was to warn you that someone you still seem to think of primarily as a cousin would be just as happy to kill you as she would be to kill a Muggle.
I know you set great store by family, but you being her family wouldn't make you safe from her. She was disgusted with Narcissa, because Narcissa wasn't happy that Voldemort had chosen Draco for a suicide mission. Said if she had a son she would've been proud to sacrifice him for the Dark Lord's Cause." The last three words practically dripped bitterness.