We'll have to wait until Sunday to find out whether Jeffrey Dean Morgan will drop into the Supernatural cast panel at San Diego Comic-Con to say hello to former co-stars (and onscreen sons) Jared Padelecki and Jensen Ackles and possibly tease a return of John Winchester to the series. But Morgan was on-hand for Friday's The Walking Dead panel and got the attention of Ackles thanks to one giant-sized character poster of of his nefarious small screen counterpart Negan.

Ackles shared an Instagram picture of himself enjoying the massive sight of Morgan's face and captioned that the image made him feel nostalgic for their Supernatural days together.

Giant posters at #comiccon2017 make me nostalgic. Keep slaying it...@jeffreydeanmorgan

A post shared by Jensen Ackles (@jensenackles) on

Morgan was featured prominently in the show's first season, as his sons searched for him, and passed away in the premiere of its second. But seeing as the show is so, well, supernatural, his character's death hasn't altogether foreclosed the possibility that he might someday return.

As executive producer Andrew Dabb told TVLine in late 2016, the possibility was still on the table, despite Morgan's busy schedule slaughtering people with his barbed bat Lucille on TWD. Dabb said, "by the time he comes back, I'm sure [Supernatural] will have been on for 20 seasons at that point, and The Walking Dead will be long over. Jeffrey's an amazing actor... He plays such a great bad guy. But at the same time... if you give him really good material, he can go back to being someone we know and love and someone we can empathize with. I have full faith in him as an actor, and I'm excited to see [him return as John] if it ever comes to pass."

That's still an if not when, but it certainly sounds like the possibility of Mr. Winchester coming back into the Supernatural fold is one that's being discussed by showrunners.

And Ackles' picture only adds to a growing list of cast interactions that suggest they're rekindling some old bonds. In January, Morgan tweeted a picture of himself in Transylvania and teased Ackles and Padalecki that he was there on official family business to take care of some vampires in the area.

To that, Padalecki chirped back, "You're gonna need more than a cigarette and a cuppa Joe... we'll be right there!" At that, Morgan said that his TV son needed some more training after all, writing, "That was holy water and a Garlic root smoke stick. So much more to teach you."

And just a few weeks prior, Morgan had sent the fellas a box of sweets from the shop he co-owns, instructing Ackles to share with his brother.

Perhaps the lucky thirteenth season will bring John back at long last, so that his kids might finally help him fight all those personal demons that haunted him so? If not, at least we'll always have this pseudo-reunion pic now.