The Big bang
The Big Bang TheoryFacebook/The Big Bang Theory

Season 9 of "The Big Bang Theory" will wind up this Thursday with the episode "The Convergence-Convergence" and it is expected to end on a romantic cliffhanger. The episode will also see Leonard and Penny exchanging vows in front of their family and friends.

Warning: This article contains spoilers from the Season 9 finale of "The Big Bang Theory."

A leaked description of the episode has revealed that the romantic cliffhanger will involve Leonard's dad and Sheldon's mom. Apparently, the duo will bond over their dislike for Leonard's mom Beverly and at the end of the episode it is implied that the duo has hooked up. Only Season 10 will reveal if their casual hook-up will turn into something serious, resulting in Leonard and Sheldon becoming brothers.

Speaking about the introduction of Judd Hirsch as Leonard's father, Dr. Alfred Hofstadter, showrunner Steve Molaro told The Hollywood Reporter that a lot of new dynamics will be explored in the episode.

"It's great to see the dynamics between him and Leonard, which is all new," said Molaro. "There is a pretty acerbic and unpleasant relationship with him and his ex-wife Beverly, Leonard. As far as what is surprising about that, there might be a bit of an unexpected attraction springing up between Leonard's father and Sheldon's mother."

This will, as expected, make Leonard and Sheldon "pretty uncomfortable."

"We leave [the season] in typical Big Bang fashion — on bit of a cliffhanger with Leonard, Penny and Sheldon in the living room making sense of everything that's going on," Molaro added.

The official synopsis for "The Big Bang Theory," according to Wikia, reads:

Leonard and Penny get remarried in front of their friends (who show up), Leonard's parents and Mary Cooper. Sheldon's mother and Leonard's father find something in common. Howard gets an unknown email from the Air Force about his invention.

"The Big Bang Theory" airs Thursdays on CBS. CLICK HERE to watch the episode live online.