To review the forces in play then:
Who's afraid of a little cliche? OK - I'll say it. It looks like it's fish tonight. Have to see what's available at the fish market (and green market) before nailing this down - but given Aunt and Secondo - it's probably some sort of white fish preparation where it's good without the sauce for Secondo and where the sauce and sides make sense given the wine and the season.
I'll post the market findings, the further decision process, and the resulting menu later.