Here’s the Story Behind The Big Bang Theory’s “Different” Season 9 Finale

If you haven’t watched yet, spoilers ahead!

Well, that’s a wrap on season nine. After the most eventful season in Big Bang Theory history (Lenny ties the knot! Shamy has coitus! A Wolowitz/Rostenkowski pregnancy! Sheldon’s a hoarder! Raj dates two women! Adam West at the 200th!), tonight’s finale didn’t quite reach the heights of shock and surprise like the episodes before it. Don’t get us wrong—seeing something potentially develop between Sheldon’s mom and Leonard’s dad was certainly eventful and hilarious. But by the time the end credits rolled, you wouldn’t be alone if you thought, Is that all there is?

Big Bang executive producer Steve Molaro explained it this way: “How obligated are we to have [these] sort of fantastic cliffhanger-y moments? Obviously [a potential pairing of Alfred and Mary] is a cliffhanger, but it’s not on the level of Leonard and Penny driving to Vegas and “Will they get married or not?” It’s a different kind of cliffhanger that hopefully still works.”

It certainly worked as a regular episode (and to the writers’ credit, it was one of the funniest), but the premise felt better suited for a special hour-long episode. Knowing that Big Bang can’t last forever, were we too greedy to hope for another major moment that would have left viewers speculating all summer long?

And about that ending: While it’s widely assumed that Mary (Metcalf) and Alfred (Hirsch) wound up in bed at the Westin, it’s also possible that that didn’t even happen. “I don’t know,” teases Molaro. “All I know is that two people met and hit it off and left to go for a nightcap. I think it’s much more interesting with us wondering what’s going on.”

Perhaps it would have been more interesting if the groundwork wasn’t laid for a possible Alfred and Mary pairing from the start. Not to always parallel Big Bang to Friends, but remember when the Friends gang went to London at the end of season four for Ross and Emily’s wedding? There was virtually no hint that by the end of the episode Monica and Chandler would wind up in bed together. Seeing them pop out from under the covers not only shocked the audience, but it also set the groundwork for one of the best arcs on the show.

But if Judd Hirsch hadn’t signed on to play Leonard’s dad, tonight’s finale could have been totally different. As the story goes, Johnny Galecki (Leonard) met Hirsch at the Jimmy Burrows NBC tribute special earlier this year, and the plan was hatched for him to come on the show. If Hirsch had said no (and we’re thrilled he didn’t), what would have happened in the finale? “It’s entirely likely that it might have worked out in a different way,” admits Molaro. “I knew that Judd and Johnny had met, and Judd had expressed interested in playing Leonard’s father, which was really exciting. We typically don’t start thinking about a finale too early, but this idea came up a few months ago [in terms of] how do we meet Leonard’s dad and why. Shortly after Leonard’s father was in the picture, we came up with this thought that there would be an unexpected attraction with [him] and Sheldon’s mother. It’s a simple idea, but it’s also outrageous.”

Even if Hirsch hadn’t become Alfred Hofstadter, someone else likely would have—so the finale may not have deviated too much from its original plan. But what about Penny’s family? After all, she invited them to the episode wedding too, right? “Yeah,” confirms Molaro. So will they arrive in time for the season 10 premiere? “There’s nothing set in stone, but we would very much like to. I can’t guarantee it, but that is planned for now. I’d love to finally meet Penny’s mother and Penny’s brother.” Although there’s plenty of possibilities (um, might we suggest Goldie Hawn?), Molaro is remaining silent on the casting front. “I do have some thoughts—and there have been some names floating around—but we haven’t dug too far into that,” he reveals. What Molaro can say is that the plan is to pick up season 10 pretty much where the season nine finale left off. “That is the plan, yes.”

In the meantime, as we close out season nine, let’s look at the big picture: No matter if the finale wasn’t what we’ve come to expect, it was still one of the series’ finest. Back in 2003 at the end of season nine, the same couldn’t quite be said of Friends.