Welp, I haven't seen one yet, so I guess it's up to me to put forth... *drumroll* the obligatory Titanic AU!

Credence is the rich young man engaged (against his wishes) to Gellert, Percival is the rakish Irishman who won his ticket in a last-minute game of poker, and they both fall in love and get married after that nasty iceberg scare, and live happily forever and ever, amen.