What's the deal with Derol in 'Glass Onion: A Knives Out Mystery'?

It was supposed to be a decadent weekend away for the elites, so rich and powerful that they could escape the fears and pandemic of COVID-19 to party on a private island in Greece. There, under the glow of the titular Glass Onion, tech billionaire Miles Bron (Edward Norton) has engineered a methodically plotted murder-mystery...