NCIS: Los Angeles will reveal the origins of a "significant relationship" in "Rage."

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Filming as episode 618 and believed to be airing as episode 20, "Rage" will peer back into Callen's (Chris O'Donnell) muddled past once more. As it does so, the story may address the origins of the Hetty/Callen dynamic.

"Watch for flashback in E618 Beginning of a significant relationship revealed. #staytuned #NCISLA airs in April," executive producer John Peter Kousakis teased.

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Callen is believed to be at the center of these flashbacks since Kousakis previously revealed that "Rage" will put "Callen, young & old" as the "major interest & focus."

Hetty (Linda Hunt) is Callen's psudo-mother, as she was with several other orphans she recruited to the ranks of NCIS, but the initial meeting has never been revealed. Many fans are hoping for another glimpse into Callen's labyrinthian early years, but it sounds like the episode will focus more on his late teens.

Do you think NCIS: LA will reveal Callen & Hetty: The Early Years? Sound off in the comments below!

Find out more when NCIS: LA airs Mondays at 10 p.m. ET on CBS. Click the video below to see a preview for the series latest episode, "Expiration Date."