'How I Met Your Mother' Creators Share Season 8 'Secrets'

(WARNING! If you haven't watched all of the last seven seasons of "How I Met Your Mother," what follows will almost certainly contain spoilers.)

"How I Met Your Mother" creators Craig Thomas and Carter Bays recently sat down with The Hollywood Reporter to let six cats out of the eighth season's bag that should get fans of the callback-loving comedy some excitement.

Keep in mind, neither CBS, nor Thomas or Bays, nor the cast have said anything making it official that the show's sunset is in sight. It's coming off a 2011-2012 campaign that delivered some of the series' highest ratings in its seven previous seasons.

However, Jason Segel is coming off a star-making big-screen turn in 2011's "The Muppets," Cobie Smulders is coming off a supporting performance in this past summer's record-decimating Marvel juggernaut "The Avengers," Alyson Hannigan is a mother now twice over, and Neil Patrick Harris has become a comedy icon of his time.

Plus, the son and daughter of Ted Mosby (Josh Radnor) are only going to sit there so long.

First and foremost, Thomas says without making an absolute, etched-in-stone declaration, this should by all rights be treated as the beginning of the end. The staff hasn't written this season as though they don't know where it's headed, he explained. There's a definitive flowchart.

"I think I can say that the premiere is the first episode of the last season of 'How I Met Your Mother'," Thomas said.

"I don't' feel like we altered it because of not knowing if it's the end," Thomas added. "We're writing this season like it's the end. We'll have to have a Plan A and a Plan B going, and we're approaching the moment when those plans diverge."

Speaking of things reaching their logical ends, expect at least one parting of the ways come Sweeps Month. Hey, that's the time when all stops are pulled, and "Mother" has three couples ripe for timely tension and/or acrimony.

In fact, Thomas promises, all come away battered and bruised in their own ways rights. Between Barney (Harris) and Quinn (Becki Newton), Ted and Victoria (Ashley Williams), and Robin (Smulders) and Nick (Michael Trucco), at least one pair will end up just two lonely individuals. 

"We've shown you the end of these relationships," Thomas reminds. "We know that Ted doesn't marry Victoria, and we know that Barney doesn't marry Quinn. We're just sort of having to show you the path of carnage that ends these relationships. All three of these breakups will be different. That's the goal of breakup month, to show you three different dissolutions of relationships."

Just the same, it's time to start writing Barney and Robin's final chapter. Thomas indicated that with last season's flash forward to Barney's wedding, "I think we've come up with a fun, weirdly appropriate way to get them back together."

Man, at this rate, isn't anybody headed for happiness? Well, actually...yes. Thomas and Bays haven't forgotten that Marshall (Segel) and Lilly (Hannigan) had little baby Marvin at last season's end. The creators suggested writers have been "careful" that they don't let the baby own the season, even though the season doesn't ignore how it furthers the growth of Marshall and Lilly's relationship.

Thomas is duly impressed with the twins playing Baby Marvin, too.

"Honestly, they're giving us better reactions than some of our main cast," Thomas joked.

Oh, and "True Blood" fans? Yeah, Joe Manganiello's back as Marshall's law school chum, Brad.

"It will be Marshall's biggest trial that he's ever had and Joe is involved," Thomas said. "We set it up last year, with Martin Short's firm." Oh, and the trial will also herald the guest appearance of Joe Lo Truglio, playing Short's hitherto-unseen firm partner.

Finally, not unlike "Scrubs" and "Seinfeld" finales before, expect many a returning familiar face.

"We have a plan to bring back many people we've had on the show," Bays said. "Not to steal their idea, but I loved the 'Seinfeld' finale where you saw everyone that's ever been on the show. We have a way to do it that sort of fits in with the universe of our show. Hopefully there will be a cavalcade of familiar faces."

The "beginning of the end" of "How I Met Your Mother" premieres Sept. 25 at 8 p.m. ET on CBS.