When my grandkid and I started telling stories together, I began with Little Old Mouse, who was inspired by the sensei mouse in Neal Stephenson’s Diamond Age. Purple Monster shortly came afterward and is entirely the creation of my grandkid. There’s a rotating cast of other characters, but Little Old Mouse and Purple Monster are the main characters. And my grandkid, of course. I take events from his day or week and incorporate them into the story. So today they made a giant snowman.