Magical Old People In Children's Books

Last night I finished reading a realistic middle grade novel in which an old woman appears way too conveniently in order to help our heroine with a far-fetched situation. She's what I think of as a magical old person, a secondary character in a children's book who appears for the sole purpose of helping the main character and providing life lessons. In my experience, most magical old people die by the end of the story, as the one in last night's book did. Because, you know, that's the very best life lesson.

Well-read child readers must catch on to the fact that if you have an old person in a book directed toward them, dollars to doughnuts you're going to have a death. Old people are like dogs in kids' books.

I want to write a middle-grade novel with an old woman who's a bitch-on-wheels. Not only will she survive the story, she may blow something up.