Quinn as Stefano's Son
Back in the 90s, it was revealed that Stefano and Vivian had a fling years prior in Europe while he used the alias "Rudolpho". It would make a lot of sense for Quinn to turn out to be the product of that liaison rather than Vivian's unnamed, random ex-husband. Imagine the sibling rivalry between EJ and Quinn. Imagine Stefano pitting one brother against the other to see who's most deserving of heading the DiMera empire. And imagine the fireworks if Quinn beds his wicked stepmother Kate! Days, please retcon Quinn's paternity and make him Quinn DiMera!