Big Bang Theory

Rick Fox inspired a rather, well, big idea while visiting girlfriend Eliza Dushku when she filmed her guest spot on The Big Bang Theory last fall.

"I met the creators and showrunners, and [they came up with] the idea of, 'Wouldn't it be interesting if I were the former boyfriend of Bernadette?'" Fox tells TVGuide.com. "I think after that, it was floated around the writers' room. ... And now here I am!"

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On Thursday's episode (8/7c on CBS), Fox plays Glenn, the hunky, 6-foot-7 ex-boyfriend of Bernadette (Melissa Rauch), who is now, of course, dating Wolowitz (Simon Helberg). He may be the definition of "tall, dark and handsome," but there's more to Glenn than, as Fox puts it, "being the guy who's on the cover on a romantic novel."

For one, Glenn is a professor with an expertise in global warming and may be just as brainy as Sheldon & Co. "Glenn looks like he would be everything but a professor, but he is one," Fox says.

The three run into each other at a science event, at which Glenn is a speaker. Naturally, Wolowitz is overcome with paranoia and insecurity, but unbeknownst to him, it cuts both ways. Bernadette is Glenn's "one that got away" and all he can do size up the geeky ladies' man's mind.

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"It's all in Glenn's head now. 'How am I losing to this guy? He's smarter than me,'" Fox says. "I love that they turned the 'threatening ex' on its ear. At the end of the day, I have more insecurity about my intellect and am constantly fighting to be accepted intellectually and be seen for more than my looks and my size. I want to appear intelligent and prove my intelligence. That's where I'm battling with him."

But will Glenn and Wolowitz battle — physically or otherwise — for Bernadette's heart, not to mention intellectual supremacy? The NBA star-turned-actor hints that the two get into "entanglements." "If we were to compete physically, I'd definitely be a shoo-in. But in this world, everything competition-wise is done through intellect. The ending is great."

Whether he wins or loses to Wolowitz, Glenn may bring his looks and brains back to the sitcom soon. Characterizing Thursday's episode as an "introduction," Fox, who also recurs on The Game, hopes it plants the seeds for a bigger arc for Wolowitz and Bernadette.

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"It was so much fun there. I had a blast. I would love to come back. I could see myself at the Cheesecake Factory, disrupting people's lives, checking them out every once in a while," he says. "He's trying to get the girl back, so he has to come back, right?"

And if Glenn comes back, perhaps he can bring Agent Angela Page (Dushku) with him?

"Eliza and I have joked about it," Fox says. "She's snooping around their lives. Here I am snooping around with their girlfriends. We can team up and snoop together!"