So, I doubt we're gonna do more than this season of romantic Batman and Robin, but... it is possible I guess. I have two theories, one with Lumen joining and one without her.

If Julia Styles gets to stay on and we do keep doing Mr & Mrs Serial Killer, Deb'll find out that the Vic on DVD #1 wan't the first, and Dex and Lumen will set up ol' girl, through the blood vial on Jordan's chain. Some sort of "We were looking for #13 as the vigilante, when it should've been the first!"

If Julia ain't comin' back, she's gonna take the fall for Dexter. I hope they don't kill her. Because that shit is getting played out. I could see her just going to jail for the crimes and keeping her mouth shut.

If they do off yet another person who knows Dexter's secret, she's gonna kill herself. Or ask Dexter to kill her.