Sheldon and Leonard, who have been best buds, are seen at loggerheads with each other lately in 'The Big Bang Theory' season 9. In episode 21, the two will engage into a heated debate, which forces other characters to take sides on the fight.

During the last episode of 'The Big Bang Theory', Sheldon's blabbermouth made Penny and Leonard fight. The drunk Sheldon spilled to Penny that Leonard has been keeping a secret bank account because he believes that Penny's credit card debt was too much. Penny was shocked to know that. But Leonard tried to calm her wife, which made Penny to also confess that she hates her job.

According to Enumerical News, Leonard may still feel angry towards Sheldon for disclosing the information without his permission. In episode 21, their disagreement will turn to a heated debate.

Christian Today reports that Sheldon and Leonard's fight divides the camp into 2. From the released promotional photos of 'The Big Bang Theory' season 9 episode 21, the 2 camps that form out of the group stay in different rooms - 4A and 4B. The other characters in the cabin are forced to take sides on the fight.

Sheldon is joined by Penny and Raj. Stuart, who is fooled by Howard into dressing up for a nonexistent costume party, joins them. Meanwhile, Leonard gets Amy's back. Amy will then reveal to Leonard how she truly feels for the roommate arrangement and how they seem to make Penny and Sheldon so close.

While it seems an unending quarrel, this may get a resolution when Howard is rushed to the hospital after eating peanut that Leonard serves to the viewing party. The gang including Bernadette, who goes home when the fight started, heads to the emergency room.

As per synopsis of 'The Big Bang Theory' season 9 episode 21 titled 'The Viewing Party Combustion': "Everyone is going to have to choose sides when a small argument between Leonard and Sheldon erupts into a heated fight during a group get-together."

Will Leonard and Sheldon be okay with each other again in this episode? 'The Big Bang Theory' season 9 episode 21 airs April 21, after a week hiatus.