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Davidson, aka actress Kelly Macdonald, stars in the franchise's final film, Harry Potter and the Deathly Hallows Part Two, and plays quite a pivotal role.
Macdonald plays Helena Ravenclaw, daughter of Hogwarts house Ravenclaw's founder, Rowena Ravenclaw.
When Harry tries to look for Rowena Ravenclaw's diadem, one of the seven horcruxes made by Voldemort to preserve his soul, he approaches the ghost of Helena Ravenclaw to help him find it.
However, she tells him that another person has asked her about its whereabouts before and tries to turn him away.
But, when Harry promises to destroy the horcrux, Helena finally tells him it is "in the place where everything is hidden", aka the room of requirement, and Harry goes to retrieve it.
Harry Potter fans were overjoyed to learn of the connection.
"Only just twigged that DCI Jo Davidson is Harry Potter's Helena Ravenclaw," said one.
Meanwhile, another commented: "JUST WORKED OUT THAT DCI JO DAVIDSON IS HELENA RAVENCLAW AND MY WORK FOR THE WEEK IS ALREADY DONE."
"I was today years old when I realised DCI Jo Davidson from #LineOfDuty is also the ghost of Helena Ravenclaw from #HarryPotter and the Deathly Hallows," said a third.
Currently, though, Macdonald is putting viewers through their paces by appearing as DCI Joanne Davidson in the BBC drama.
Now Acting Detective Superintendent for the Murder Investigation Team, it looks likely that Davidson has links to the OCG.
Fans are convinced she's a bent copper, after witnessing her using a private chatroom to communicate with an anonymous person at night, her secret burner phones and her suspicious involvement with new police recruit Ryan Pilkington, who has been placed inside Hillside Lane Police Station by the OCG.
Sadly, we'll have to wait to find out just how exactly Davidson's involved with the crime gang.
Line of Duty airs on BBC One at 9pm on Sunday evenings.
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