Pippina
A hitherto neglected Goddess on the Discworld. Pippina is the Goddess of Disorder and carries the Golden Apple of office. It presumably caries a suitable Ephebean aphorism, possibly one suited to the occasion and bespoke to the situation. "Kallisti" is most suited to an exaggerated sense of entitlement and the sin of vanity, after all.
On the established principle of divine moonlighting, Pippina may be a specialised aspect of the pre-existing deities Hoki and Errata.
Annotation
Pippina has a lot in common with Roundworld Greek goddess Eris (Rome's Discordia), who famously took revenge for being excluded from a wedding reception by crafting the golden apple inscribed "KALLISTI" - to the most beautiful - and throwing it into a room full of her fellow Goddesses, knowing full well there'd be a cat-fight and that their male consorts would be forced to take sides. She then sniggered, stood back, and watched the divisions on Olympus surface on Earth as a devastating ten-year war between Greece, supported by one divine faction, and Troy, supported by another. We all have to get our amusement where we can...