- Associated Press - Sunday, February 5, 2012

The mysteries that surround the CBS sitcom “How I Met Your Mother” extend to co-creator Craig Thomas’ office on the Fox studio lot.

A white board on the wall that outlines the seventh season’s episodes ends with Barney’s wedding in the May finale. ” ____ is the bride,” the board says.

You never know who’s going to walk in, and Mr. Thomas and partner Carter Bays hold tight to their secrets. That will be a pivotal episode: Not only will the ultimate bachelor come off the market, but the show has revealed it’s also the day Ted meets his future bride — the mother that is the conceit upon which the entire show is built.

That doesn’t necessarily mean viewers will meet the mother in that episode, however. Stay tuned.

This has been a big year for the comedy that launches CBS’ Monday nights. Ratings are the best they’ve ever been, up 19 percent over last season, and it has the youngest average audience on the network’s prime-time schedule.

“There’s almost no scientific explanation, and we couldn’t have counted on that,” Mr. Thomas said.

Time may make viewers more invested in the lives of Ted (Josh Radnor), horndog buddy Barney (Neil Patrick Harris), Ted and Barney’s ex Robin (Cobie Smulders) and the married couple Marshall and Lily (Jason Segel and Alyson Hannigan).

Another likely contributor is the boomerang effect of syndication making more people familiar with the series. “How I Met Your Mother,” which just filmed its 150th episode, has been seen outside of prime time on local broadcast stations the past few years. Last year it also was on Lifetime, the cable network targeted at women, and this fall added FX, which is popular with young men.

The FX showings began with a Labor Day marathon and a clever ad campaign that pictured the cast and suggested: “Isn’t it time you made some new friends?” “How I Met Your Mother” hit the syndication market at the time there was a relative paucity of new comedies and reruns of “Friends” were getting tired from overuse.

“How I Met Your Mother” is the closest TV has to a modern-day “Friends.” It started at a time, in 2005, when networks were desperate to replace that beloved NBC series and, frankly, the namesake gimmick distinguished it from other wannabes. The series opened with children on a couch impatiently listening to narrator Bob Saget, as Ted circa 2030, explains how their parents met.

That first episode began with Ted establishing a romantic connection with Robin, ending with the kicker of Mr. Saget explaining, “That’s how I met your Aunt Robin.”

During an initial meeting with TV critics before the premiere, Mr. Thomas and Mr. Bays were taken aback by anger they faced about that pilot’s twist. Were they really expecting to learn the mother in the first episode? Then they realized: People cared about the characters they created.

They don’t regret the structure, even if “who’s the mother?” is no doubt the cocktail party question they’d least like to hear by now.

“I always thought the frustration about it was a little misplaced,” Mr. Radnor said. “There’s so much to enjoy beyond the central conceit of the show that I always felt like, ‘Relax.’ If he meets the mother, the series is done, so if you like the series you should be waiting. Enjoy the wait.”

Many fans believe the mother should be revealed on the final episode. Others would like to see the future parents go through their first year of dating. This much Mr. Thomas will say: It will be one of those two possibilities.

That’s why Mr. Thomas and Mr. Bays have some important meetings ahead of them this spring. The actors are signed through the end of next season (May 2013), so the producers will need to know soon if the series is stretching beyond that.

Revealing when Ted would meet his future wife turned out to be liberating.

“It’s kind of a momentous thing to say,” Mr. Thomas said, “because it retired one of the tricks on this show that we had milked for half a decade, which was that any girl that Ted bumped into anywhere could be the mother. Last year we said we’d done that enough.”