Jim Parsons Says Sheldon Is Ready to Kill on 'The Big Bang Theory'!

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The Big Bang Theory star, Jim Parsons, revealed to ET that his character, Sheldon, is on the defensive over girlfriend Amy on Monday night's episode.

Sheldon finds himself in an awkward position when his co-worker, Barry [John Ross Bowie], expresses interest in Amy [Mayim Bialik]. The situation is heightened when the guys take a fencing lesson from Barry.

WATCH: 'Big Bang' Stars on Sheldon & Amy's 'Rough' Breakup

"He threatens to kill [Barry]," Parsons told ET on set last week. "He challenges him to a duel, and then later tells Amy, 'Don't get too attached. In a few years he's going to be a dead man.' So who knew he had such strong feelings and a violent streak? But apparently he's at least intellectualizing violence."

Clearly things between Sheldon and Amy are going from bad to worse in the show's ninth season after last season's brutal breakup, but could this be the spark Sheldon needs to inspire him to win Amy back?

Watch The Big Bang Theory on Monday nights at 8 p.m. ET/PT on CBS to find out.