Speaking at the Television Critics Association's winter press tour, Nevins insisted that the possibility of romance between Dexter (Michael C Hall) and his adoptive sister Deb (Jennifer Carpenter) had been on the cards "for a long time".
"I'm aware that there's a certain taboo, despite the fact that they're not genetically related," he said. "But [this is] something that has been building over a number of years."
Nevins also explained the decision to have Deb uncover Dexter's murderous ways in the recent sixth season finale.
"[It sets] a very clear trajectory [for] the next two seasons," he suggested. "It's going to help to write with that endgame in mind.
"There should be a fundamentally different dynamic now that Deb [knows about Dexter] and it's going to ricochet."
Dexter was picked up for two more seasons in November. At the time, Nevins indicated that the show was likely to end at the conclusion of its eighth run.
However, he has since hinted that a ninth season of the serial killer drama is a "possibility".
"This is the likely endpoint, but... plans could change," he said at the TCA press tour.
> Michael C Hall: 'Dexter may not have a happy ending'
Watch Dexter showrunner Scott Buck discuss the sixth season finale below: