On the heels of Supernatural returning with new episodes, executive producer Jeremy Carver teases what is still to come for the brothers and the Mark of Cain.

In the aftermath of the so-called massacre at the ranch, Sam and Dean were more determined than ever to remove the Mark of Cain from Dean. In the mid-season premiere, the brothers were desperate enough to turn to Metatron for answers, though that went about as well as could be expected.

So what comes next for the brothers? After Metatron fell through, another source of information is the man Dean got the Mark from: Cain. And yes, Tim Omundson will be back later this season.

According to Carver, “Dean’s interaction with Cain will have a profound effect on Dean, how he thinks about the Mark, and how he thinks about himself with the Mark.” He adds, “It’s a pretty wonderful episode and what it means for the season-long arc is pretty dramatic. We’re excited about this episode.”

Something the Winchesters are particularly intent on finding out is whether Dean is truly human with the Mark or if, despite being cured, there is something more. “What we do know is when he was killed last season, the Mark wouldn’t let him die. He came back as a demon,” Carver says.

“Had he stayed a demon, one could argue that he was immortal in the way a demon is, because Cain is a demon and he’s been a demon for the last several hundred years. The question is, Dean as a human with the Mark, will the Mark ever really let him die? That’s a very profound question for him, and it’s one that he will ask.”

As for how the brothers will deal with each other, Carver teases, “The brothers are going to be in concert with some things, not in concert with some things.” So what does that mean for the brotherly relationship? “It’s going to be a little bit of both allowing Sam to help and taking it on himself,” Carver explains.

“The boys are going to be open with each other and not open with each other at the same time when it comes to the Mark. Dean’s not going to completely admit how it bothers him sometimes, but Sam is not a dummy. He knows how it’s affecting Dean now, but then again, he might not always say how he knows it’s affecting Dean. It’s the elephant in the room as the season heads to the end.”

Supernatural airs Tuesdays at 9:00 p.m. ET on The CW.