Carabas

3rd person. Two sisters were raised by their grandmother, and the grandmother favored the younger one over the older one, to a ridiculous degree. The older sister confronts her grandmother on this, which she's done a thousand times before, but this time the grandmother tells her a story about her past. One day the grandmother's wayward daughter, who'd disappeared months before, just turned up on her doorstep with a girl who looked about 4 years old, a creature created by magic. She didn't explain where she'd been or what she'd been doing all this time, she just left the creature and disappeared again. Now the grandmother feels she's done her duty by the little monster just by taking her in and raising her at all, so now that the truth is out, she expects the older sister to understand the favoritism and quit complaining.