Will Katherine’s (Nina Dobrev) unexpected knowledge of the fall of the Holy Roman Empire ruin her possessing-Elena ruse? In this sneak peek for Season 5, Episode 14 (“No Exit”) of The Vampire Diaries, Stefan (Paul Wesley) is helping Katherine study for a test — and it’s kind of adorable. So adorable, that Katherine nearly forgets that Elena’s knowledge of European history might not be as rock solid as her own. Check it out!

Stefan and Katherine are studying in the Salvatore mansion library in this TVLine exclusive sneak peek at Thursday’s episode. “Roman Empire?” Stefan fires at Katherine. He is looking quite comfy as he lounges on the couch, textbook in hand.

Katherine, perched on a desk on the other side of the room, doesn’t miss a beat: “476 A.D., sacked by the Goths.” The two barrell through the fall of the Han dynasty before getting hung up on the Romans.

“Not really an empire, but 1648,” Katherine informs Stefan.

“There goes your perfect score,” Stefan tells her, which spurs Katherine to make her ways over to the couch to check the textbook herself. We love that she can’t stand to be wrong. “No, that was right,” she says, putting a hand on his shoulder and leaning in to check the book.

Stefan stands by his answer: “No, no, no. The book says 1806.”

Katherine clarifies how she is right: “OK, may technically be right, but it was the Peace of Westphalia that truly ended the empire and that was in 1648. Trust me.” Katherine seems to realize she went a little too far with her historical knowledge -- or should we say, memory. And she’s right: Stefan totally looks suspicious. “I may have done a paper on the Holy Roman Empire in high school,” Katherine continues. Nice cover, Kat!

“Well, if you wanna pass the test, I suggest you write down exactly what’s in the textbook,” Stefan says, letting his suspicions go. A relieved Katherine nods as the doorbell rings. “Caroline’s here. I asked the sheriff to help me track down Damon.” And... her relief is over. Katherine is not excited about this particular brother quest. It seems she’d rather spend the entire day debated the fall of the Roman Empire with Stefan, which — as messed up as this entire scenario is — we still find kind of sweet.

Catch the next episode of The Vampire Diaries on Thursday, February 27 at 8 p.m. ET on the CW.

Kayti Burt is a contributing writer for Wetpaint Entertainment with a penchant for all things pop culture. Follow her on Twitter and Google+!