SPOILER ALERT: This interview reveals major plot points from the “9-1-1” Season 6 finale, which aired Monday on Fox.

Buck (Oliver Stark) helped bring a very special baby boy into the world on the sixth season finale of “9-1-1.” The little guy, whom Buck donated sperm to help his friends conceive, was born on Buck’s new couch (if you know, you know) — with Buck delivering the infant during one of the most large-scale disasters “9-1-1” fans have ever seen.

“9-1-1” is moving to ABC for its seventh season, meaning, unfortunately, that any future crossovers in the franchise are “extremely unlikely,” according to Fox boss Michael Thorn. For the final episode of “9-1-1” that will ever air on Fox, Stark spoke with Variety about his experience filming it, and what he hopes for Buck’s future.

Buck helped delivery his friends’ baby — whom he helped conceive — on his couch in this episode. What was that like for Buck (and you) to experience with all the complicated feelings that surround this and that we have been exploring since Buck agreed to be a donor?

It was very fitting that he be the one to deliver the baby — we’ve seen him go through a roller coaster of emotions when it comes to this baby. There have been possibly times when he was feeling a little bit too connected to the whole thing, and then I think he withdrew himself and was able to put himself in the box of purely donor. But I think then the arrival of the baby and being the one to deliver it and holding him in his hands is obviously going to bring up a whole new load of emotions.

The day before we filmed that scene — it was well-intended, but it certainly put a new pressure on me — a crew member told me that she had been through this situation. She had had a baby, knowing that she was going to be giving it away, and spoke to me about some of the emotions that she felt and then said, “So I’ll tell you if you do a good job tomorrow.” Thanks, no pressure! But it was really helpful, and we have Brad Buecker directing the episode — who has been so integral to everything “9-1-1” is — but then also to have her on the set, and to be able to have conversations with her was a huge help to me and really made the experience, I think, that much more special.

Buck’s budding romance with death doula Natalia is given a good amount of screen time in the finale. Where do you think it’s going from here?

I’m really excited about the relationship forming between Buck and Natalia. Annelise Cepero, who plays Natalia, is such a wonderful actress, and is really just fun to be around, fun to work with. I love getting to play these things out with her. And I just think it’s something different for Buck, in the sense that she hasn’t taken these things that have happened to him and treated him like he’s the victim, and that he is this sad sob story. She has sparked this light in him, and is excited about things that he’s been through; not in a sense of taking advantage of them, but of them being interesting and them making him who he is. She’s actually a really positive person to have around, and I’m looking forward to what I hope will be continued growth between them and we’ll get to see that relationship and that connection filling out more and more, hopefully, in Season 7.

What do you want for Buck in Season 7?

Kind of piggybacking off of what’s happened this season, we saw in the early episodes, he wanted more responsibility. He thought he was in a position to be interim captain, told that he wasn’t. And now at the end of this season, in the finale, we really see him using the experience that he’s gained and really stepping up. And even though he’s not officially the captain in that situation, and Hen is by name the captain, he really takes control in the scene.

And so I think a continuation of that, he’s using these experiences that he’s going through, and he’s putting them to good use and he’s putting himself more and more in a position where seniority and responsibility can be placed on his back, which I think is a really important thing for him. I would say just continued growth into possibly, one day, stepping into a role of more authority.

This interview has been edited and condensed.