Even though the role of Bess Sinclair was written with Candice King in mind, “We Were Liars” co-creator Julie Plec says there were many early conversations that she was too young to play the part.

In the new Amazon Prime series, King, 38, plays Bess, the seemingly perfect high-society mother to three daughters — the oldest of whom is 16 years old.

“When I first started writing scenes with Bess in them, I said to [co-creator Carina Adly Mackenzie], ‘I know she’ll never get this part ‘cause she’s too young, but all I hear is Candice’s voice in my head,’” Plec tells Page Six.

Mackenzie told Plec that while King — who is real-life mom to daughters Florence, 9, and Josephine, 4, with ex Joe King — was young, she has an “old soul,” so perhaps it would work out.

Two years went by before King eventually went in to read for the role.

“She came in and auditioned for it because she wanted to sort of prove to us that we were wrong about her being too young for it and she just blew our minds,” the “Vampire Diaries” co-creator explains.

“We were able to proudly show her audition to everybody without saying a word. Not like, ‘Oh, we really want this person in the show,’ just like ‘check out this great audition’ and she got the part.”

Plec and King began working together around 2009 when the latter was cast in “Vampire Diaries” as Caroline Forbes. King later reprised her role on Plec’s spinoffs “The Originals” and “Legacies.”

Plec says that she and Mackenzie, previously a writer for “Originals,” stayed in close contact with King after the hit vampire series ended.

“It was really exciting to work out that way because it’s really wonderful when you can work with people who you really admire and love, and know they’re a good human,” she tells us.

She adds, “To be able to go on this adventure with Candice is really special.”

Plec also says she’s blown away by the talent they were able to get on the show, especially actor Joseph Zada, who is set to star in the “Hunger Games” prequel “Sunrise on The Reaping.”

“There’s something kind of extraordinary about him and I’m looking forward to seeing his career flourish,” she says.

“We Were Liars” — which premieres June 18 on Amazon Prime — is based on the 2014 YA thriller by E. Lockhart and follows teen Cadence Sinclair as she tries to remember a traumatic incident that occurred on her wealthy family’s private island.