"That very first time he and I sat across each other and exchanged the words, it was all there."
Although the show's cast and crew were full of praise for The Cul de Sac star, Apa almost didn't get past Riverdale casting director David Rapaport, who watched his early audition tape and declared, "I just don't see it".
As the six-month search for Archie neared its end, Rapaport reevaluated Apa's suitability and convinced executive producer Roberto Aguirre-Sacasa to present the Kiwi alongside other final contenders to the network.
"He was jetlagged and had just gotten to LA from New Zealand and David brought KJ in and said, 'Stop the presses, you have to see this kid. I think he's Archie.'
"I said, 'Does he have red hair?' and he said, 'No, he has really dark hair'.
"I went, 'Okay, is he kind of all-American?' and he said, 'No, he's from New Zealand and half-Samoan'.
"But he read the scene and it came to life in a way that no other actor had done.
"It was completely unanimous."
For Apa the prospect of playing such an iconic figure was daunting.
"It was nerve-wracking at the beginning, coming from New Zealand and playing such an all-American character," said Apa.
"I was scared the aggressive Archie fans would be unhappy with a non-American playing this character, but it ended up not even being a thing.
"I didn't hear anything like that."
Apa was part of a strong Kiwi presence at the annual convention. Actors including iZombie's Rose McIver, The Originals' Daniel Gillies, Cliff Curtis and Antony Starr were at the event promoting their shows.