The Riverdale panel at the Warner Bros. TV Block at New York Comic Con Sunday morning began on a somber note (after a hook-ups and séance-filled sneak peek at next season), with the cast members recalling Luke Perry, the beloved TV icon who passed away suddenly on March 4 while the series was in production for season 4 (premiering Oct. 9 at 8 PM on The CW).

Now into filming for the new season, showrunner Roberto Aguirre-Sacasa and five of the parent players recalled the giant loss of the man who played Archie Andrews’ father, Fred, a loss that’s dealt with in the first episode of the new season (which will costar Perry’s longtime 90210 heartthrob, Shannen Doherty). The panel afforded the cast the opportunity to have a more extensive remembrance of Perry than the Riverdale panel at San Diego Comic-Con this summer.

The panel also served as a vehicle to premiere the trailer for the upcoming season.

“It was very difficult for us all,” said Skeet Ulrich, who plays Serpent-turned-sheriff F.P. Jones. “To me, in some ways, it meant reliving something incredibly painful. We felt the need and the want [to pay him tribute]. But I don’t think any of us wanted to live in that again—[the first episode of the season was] a beautiful episode, but incredibly hard to perform.”

“For me, it was very cathartic,” added Molly Ringwald, Fred’s ex-wife, who’s returned to Riverdale. “I think we all dealt with it in different ways. I didn’t get to go to Luke’s memorial so [this episode] was really like my good-bye to him. It was kind of what I needed. He was my guy. It felt like a nice good-bye for me.”

“It just puts a lot of things into perspective,” added Mark “Hiram Lodge” Consuelos.

“It’s funny, Luke passed, and we had two episodes after that and when you come back you’re right back in the incident,” added Marisol Nichols, a.k.a. Hermoine Lodge. “It’s like, you expect to see him at Pops, or there was his trailer. His spirit is still with us.”

That absolutely becomes the case, as this season explores some very mature themes, starting with the moment Archie gets the phone call that brings home the terrible news. That’s mature in terms of content (steamy scenes include a kiss, and no doubt more, between F.P. and his ex-wife, Gladys, played by Gina Gershon), and mature regarding the great deal of growing-up characters must do this season.

“The one thing bringing the parents together this year is the kids are graduating and the theme is seeing all the kids become adults,” said Aguirre-Sacasa.

Perry’s loss will also be felt in terms of where F.P. is headed. “Fred was really F.P.’s moral compass, and now Mary is taking the place of that for him,” said Ringwald.

Other surprises fans can expect in season 4 include the introduction of Veronica’s sister (“She’s not my daughter,” joked Nichols), more hints on action for Sabrina, a memorable Thanksgiving episode, and some potential action between Alice and F.P. “When and if Alice escapes the farm, she’ll be living in the same house as F.P.,” said Aguire-Sacasa. And when an audience member asked the panel if there’s anything fun they’d like their characters to do that they haven’t done yet, Ulrich brought the house down with his one-word, mic-drop answer: “Alice.”

But Perry’s spirit still hung over the proceedings, as moderator Damian Holbrook of TV Guide Magazine summed it up, “Like life, you go through a loss together, and then you go back to it. But you have certain things that won’t change in Riverdale.” The nostalgia and the present were inextricably linked. Said Aguirre-Sacasa, “I loved it when Luke auditioned. I grew up watching him on 90210.”