As the preceding episode of Season 9 left more questions than answers on how Sheldon's mother (Mary Copper) and Leonard's father (Alfred Hofstadter] fared well, the premiere season plot gives a preview of a steamy development.

Leak report disclosed that, in the opening scene, Sheldon, who is sleeping on bed, confronts Leonard, who is sleeping with Penny in their room through a wall, on the possibility of them becoming brothers.

But Leonard acted outrageously, saying they could never be brothers or stepbrothers. But the famous Sheldon Copper went further, "Is your father doing despicable things to my mother right now?"

The expectation of their parents' hooking up is further strengthen when Mary and Alfred arrive at Sheldon and Leonard's apartment together.

Amid awkward silence upon their arrival, Sheldon stuns everyone in the room when he asks Alfred, "So, did you defile my mother?"

"I can assure you we only had drinks and pleasant conversation," answered Alfred to Sheldon.

The pilot season episode will also deals with Leonard and Penny's second wedding attempt.

Penny' mother Susan (played by Katey Sagal) and brother Randall (played by Jack McBrayer) will make their first appearances in the show.

According to the report, Penny will share a funny scene with her family in the car, however, her mother is very worried about what Leonard's parents will think of them. The episode will focus on the families of Leonard and Sheldon as Beverly, Leonard's mother, will also make her appearance.

Do not miss the premiere of "The Big Bang Theory" Season 10 on Sept. 19 to find out more about Sheldon and Alfred's discussion and Penny's dynamic with her mother and brother.