"I didn't care if I died," he said.
Listen to "The Remarkable Life of Sonny Fai" on Spreaker.
For the first time the harrowing details of the evening of January 4, 2009, are revealed through the eyes of those who were on the scene, including Lesi Fai, his sister Colleen and Bryn Grant-Mackie, who had just completed his first patrol as a qualified lifeguard when he was made aware of the family's struggles.
Lesi carried the burden of guilt with him for many years and it was a reason he joined family in Sydney when some relocated after Sonny's death.
He immediately made an impact on the local league scene with his pedigree and impressive frame, and quickly progressed through the age grades.
In 2015 Lesi was signed to the Bulldogs U20s team for the NRL feeder competition the Holden Cup.
But his heart was never in it.
"He just walked away," his older sister Lalelei Fai Tupulua said.
"The way he explained it was, the only reason he played rugby league was because he felt like he owed it to Sonny. He chased that career for Sonny.
"But in his heart, it wasn't his passion to be a rugby league player."
Lesi lives in Perth with his partner, Mel Smith, and works as a builder for his father-in-law. His dream is to one day have his own building company.
"I'm glad he did, because that said to me that my baby brother has moved on from all his guilt. He blamed himself for Sonny not being here, he blames himself that Sonny went out to save him," Fai Tupulua said.
"He took on that guilt and as a 13-14 year-old... So when he came and told us he was walking away - yes, we were disappointed, but at the same time, we were happy for him. It was an indication he has moved on."
Sonny Fai's death has haunted the Warriors since that fateful day in 2009 but it was nothing compared to the impact it had on the family, with Fai Tupulua saying it caused a split that took a long time to heal.
Fai Tupulua revealed that she had a nagging sense of unease when Sonny asked to borrow the keys to the family van on that fateful day.
"Normally on a Sunday afternoon me and my husband would take him for runs, like we go to Maraetai Beach and he'll just run the sand there," she said.
But Sonny Fai wanted to take some family members out to Bethells Beach to show them where the Warriors completed some of their rigorous off-season training; including the beach's steep sand dunes.
"That was the first Sunday that we didn't take him. I don't know why, but I just hate myself for not taking him.
"But he just begged and begged and we ended up giving him our keys."
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