Still playing about with it, but leaning toward one of the nastier Puss-in-Boots variants. And I opened it up with the dying father offering his sons a choice between his blessing and his goods. One takes the blessing, and the other the goods, and of course, the second is the one the tale's about.
And I had been wondering whether to have another character hear a story in another place where she's holed up for winter, and then I realized I had a dangling thread, since the first son just vanishes. Happens often enough in tales -- sometimes there are two older brothers or sisters who serve no plot function except to make the youngest the third -- but in a land where they are true, it's a loose thread.
So I was wondering what sort of tale to put him in. Perhaps -- perhaps -- one of the nicer Puss-in-Boots variants?
I shall have to ponder that. Perhaps even write them and see if the contrast is enough.