SPOILER ALERT: Do not read if you have not watched “Timing Is Everything,” the March 15 finale of “How I Met Your Father.”

The finale of “How I Met Your Father” didn’t reveal who the father is — but it did give fans a cameo from the original show they’ve been waiting for. During the Season 1 finale, Sophie (Hilary Duff) and Jesse (Chris Lowell) finally get together, in a relationship so brief that, by the end of the episode, they’re already done.

After Jesse tells Sophie that he ended things with Meredith (Leighton Meester), the pair spend the night together and he mutters “I love you” in his sleep. When she playfully brings it up ahead of her gallery debut, he explains that it’s not a big deal because he turned down going on tour with Meredith for her — something that is a bit scary for her. After she expresses that, he asks her to leave and she heads downstairs to a little bar called MacLaren’s. (Of course, this is the spot that the gang gathered in during nearly every episode of “How I Met Your Mother.”)

When she arrives, not only does she order from Carl the Bartender (Joe Nieves), she is greeted by the one and only Robin Scherbatsky (Cobie Smulders), the perfect person to give her advice about a man moving too fast. Sophie — starstruck since Robin is now a very famous reporter — explains her heartbreak to Robin, who wants to help.

“I once had a guy say ‘I love you’ on our first date,” she says, referencing Ted (Josh Radnor). When Sophie responds, “Dude sounds like a real piece of work,” she shares more.

“You have no idea,” Robin tells her. “But a good piece of work. Which brings me to my advice: Do not waste your time being scared, Sophie. Fear can make you run away from things that could be good — great even, things that are supposed to be a part of your story. So, really think about it: What did Jesse do wrong other than say everything you ever wanted a guy to say, just faster than you expected.”

Afterward, Sophie runs back upstairs, but stops when she sees Jesse kissing Meredith. She walks away before he can see her, returning to the bar to tell Robin what happened. Still optimistic, Robin tells her, “If I’ve learned anything at all about love, it’s that timing is everything. Sometimes, timing’s a bitch.”

With that, they make a date to meet again in 20 years.

Showrunners Elizabeth Berger and Isaac Aptaker broke down the finale episode, gave details about Robin’s surprise appearance and talked about what’s coming in Season 2.

Diving right in, how and when did you decide that Robin would be the one you’d bring back?

Isaac Aptaker: We started talking about it pretty early in the season. We always knew we wanted to play with bringing back characters from the original, but we were also very adamant that this was a show that forms its own set of characters and its own group of friends first. So we knew we didn’t want that to happen too early. We also knew that when we wanted to bring back characters, we wanted them to have something really important to do — to guide one of our characters on their journey. Robin is coming into our show at an essential point in Sophie’s life and helping to point her in one direction. So it felt really organic that in our finale when Sophie’s at this romantic crossroads, that she would cross paths with with Robin and get some advice from this wiser character who’s in a different point in their life.

Was it always going to be Robin, or were there discussions about Josh Radnor, Jason Segel, Neil Patrick Harris or Alyson Hannigan?

Elizabeth Berger: There were absolutely discussions, and there continue to be discussions about who else would be fun and what way they’ll be utilized. This sort of clicked in very early and felt right. We loved the idea of them having this talk woman-to-woman and commiserating about their love lives and about timing. Once we started circling that idea, that became the winner early on, and we decided we’ll save all those other ideas for a little bit down the road.

Robin says, “I have been married, I have been single, I have been everything in between. The only decisions I regret making are the ones that I made out of fear.” She has no ring on and doesn’t mention Ted directly. Was that all deliberate?

Aptaker: Yeah, it’s all very deliberate. We worked with [original creators] Carter [Bays] and Craig [Thomas] pretty extensively on that scene together. We gave out exactly the amount of information that we all felt when we were ready to give out about Robin. I mean, we’re coming back and doing 20 more. There’s a lot more to tell both of our gang’s story and tidbits about what the “How I Met Your Mother” crew is up to. Everything in that team was very intentional and what we were ready to tell viewers at this point.

Well, MacLaren’s as a location was such a big character in the original too. Now that the set is up again, will you be back?

Aptaker: 20th Television has this warehouse on the outskirts of L.A. where they keep all these iconic sets from their long-running shows. We weren’t sure if we were gonna have to build it from scratch. And then lo and behold, just like with the guys’ apartment — the walls of it at least, were just there waiting for us. Our incredible production design team looked at all these archives and records and found as much of that original decor or replicated it. So yeah, it’s out there, should we ever decide to return it.

You also finally solved “The Pineapple Incident” mystery, something that fans of the original show never got the answer to unless they watched the later-released deleted scene!

Aptaker: Yeah, that was an unanswered question, one of the dangling ones [from “How I Met Your Mother.”] That’s actually to Craig and Carter’s credit. They were like, “What if we threw it in here?”

This finale ended with Meredith and Jesse kissing. What can you say of how much Leighton will be in Season 2?

Berger: We don’t want to say too much. Obviously, we see them kiss at the end of the season, so there’s definitely still something there. That being said, we think it’s possible that viewers could think they break away from that kiss and Jesse says, “Oh, my God. What did I do?” and backs away from her or there’s a possibility that they’re headed off together. That’s sort of up in the air as we move into Season 2.

Aptaker: What I want for Leighton Meester is more singing. That song, we only play a tiny bit of it on the show because the episodes are so short but she recorded more of a full-length version. She’s so talented and it was stuck in everyone’s head on set for the entire week. I want to record more music on the show with her.

Berger: We really believe that “Jay Street” would climb the charts if we released it.

Sophie and Jesse obviously have a longer arc coming. What can you say about that?

Aptaker: They’re at a really interesting place where they’ve had this season-long friendship and there was obviously something more there. Then, as soon as they decided to take that leap, it went south very fast. They didn’t even make it 24 hours together before things fell apart. So now they’re in this really, really complicated place in a group of friends. They tried it, it didn’t go so great. There’s obviously still feelings there. But she walked in on him hooking up with his ex moments after they split up, so they’re in a really really precarious place as friends and as a new potential couple.

Obviously you know who the father is. Do you also know right now who is endgame for Sophie right now?

Berger: We have a very loose plan of the ending. I mean, we obviously come from the “This Is Us” world. So we’ve learned over the last almost full six seasons how important it is to have sort of the big moves of your plan mapped up out while still leaving yourself the room and the freedom to pivot or to push a little bit from what you expected. We really are people that have locked into the importance of having a plan, and we definitely have one as we as we go forward.

Season 2 is going to be 20 episodes, which is pretty unheard of for streaming these days. How’d you decide on 20?

Berger: It’s a decision that is above our pay grade. We were thrilled to receive it. It was very surprising. I think that Hulu weighed a bunch of different factors, everybody did. This felt, to everyone, what was best for the show, and we’re thrilled. We certainly think it’s best for the show. We love doing our 10, but it did sort of put pressure on every episode to sort of move along our romantic serialized arc in a way that you just have to do when you have such limited real estate. We can let our arcs breathe, we can let our fun, less-serialized stories breathe — and just do those crazy, hanging-out-till-dawn episodes if we want to. So we just think it’s so great from a storytelling perspective.

So many other big relationship updates happened in the finale. Will Season 2 pick up right away or have a time jump?

Aptaker: Good question. I mean, there’s a lot left on the table right there. So we definitely are going to revisit the immediate events. We literally cut to black, so I think we’re certainly going to see what happens the rest of that night, whether we do it linearly or jump around a little bit before we get there, I think people are gonna have to wait and see.

Lastly, is there a chance that we have not met the father yet?

Berger: Of course there is a chance. You know, we obviously chose our language very carefully in our first episode. Future Sophie says, “That’s the night I met your father.” So we know that we could potentially return to that night. Obviously, that’s something we want to do very sparingly, should we choose to do it, because we don’t want fans to revolt against us and say, “Hey, you’re just going back to that night 100 times!” But there is always a chance.

This interview has been edited and condensed.