He's a candidate to be the NRL rookie of the year, yet he couldn't even make the under 15s A team at Keebra Park. Back then, like Benji Marshall before him, touch football was AJ Brimson's main love.
In 2013, the Titans teenager of the moment was billeted alongside Queensland teammate Kalyn Ponga with a family in Darwin during the national under 15s schoolboys touch football championships.
Ponga – a Broncos scholarship holder who already had five other NRL clubs chasing him – was the standout player in the Queensland side that were runaway title winners.
Meanwhile, Brimson went back to Keebra Park where he was little known – in rugby league at least.
He was good mates with Brent Woolf, son of Keebra Park High School teacher and footy coach Ben Woolf who saw potential in Brimson that wasn't shared by everyone. He was impressed by his attitude.
Brent would drive to work early with his father two to three times a week for 6.30am weights sessions. AJ would leave home just after six and ride his bike to school to join them.
In 2014, Woolf tipped one of Gold Coast's Cyril Connell Cup (under 16) coaches that he had a kid with raw talent who was worth giving a trial run. Brimson turned up with a score of other hopefuls, up against the celebrated teenagers who were already earmarked for automatic selection.
He impressed so much, he was the first halfback chosen.
It was the first rep team he'd ever made and so ecstatic was he and his mother, who he lived with at a string of different locations in Brisbane and Gold Coast in those early years, went out to dinner as a special treat to celebrate.
The trajectory of Brimson's career has been up ever since. Two years later he made the Gold Coast Mal Meninga Cup (under 18s) side that had Titans stalwart Greg Bird as its assistant coach. He was not only player of the year in the team that made the finals but was the Cup's player of the year (won jointly with Norths' Gerome Burns).
But never did he think he would oppose Ponga, as he did in round 11 this year, at NRL level while still a teenager. Nor would he dream that he might end up a long-term NRL fullback like Ponga, which seems his destiny after an impressive debut in the position against the Panthers last Saturday after 11 games in the halves.
"KP played in Brisbane and had massive wraps on him," Brimson enthused. "We roomed together with a family in Darwin and he was our standout player and player of the tournament I think.
"Footy wasn't my priority then. Although I played weekends, it was all touch footy until I was at Keebra Park and Ben Woolf said to go and try out for the Cyril Connell Cup team.
"That was the turning point. You had to take league seriously at Keebra because they trained so hard and I got in the gym and got stronger and fitter and that transitioned into Cyril Connell footy.
"I was rapt to make that team; I was 15 and it was a big thing and mum took me out to dinner to celebrate."
Woolf, who coached Brimson in the Titans under 20s in the second half of 2016 after Brimson graduated from Mal Meninga Cup footy, recalls vividly how he was captured by Brimson's work ethic around his raw touch football skills.
Brent was one of the halves who kept AJ in the Keebra Park seconds team but their friendship was the catalyst of Brimson's progression to NRL.
"I ran a gym session in the morning and mates would meet Brent there but soon drop off," recalled Woolf.
"Not AJ. He'd get himself up early, ride to school and showed real commitment. It was all self-motivated. He got himself stronger and faster.
"He was fast and skilful but lacked size and strength and I guess confidence.
"I made sure he was in the Titans academy squad when I joined the club the next year. He'd done nothing at that stage but I just knew his work ethic was so good and he always had the speed and the step from touch football to develop into a good player.
"He wasn't a good defender as a kid but now it's one of his biggest strengths."
It was Woolf who first switched Brimson to fullback in 2016. St George Illawarra's Matt Dufty was the Holden Cup's standout fullback that year and Woolf thought Brimson was similar in body shape and speed.
Manly centre Brian Kelly was playing fullback for the Titans but had to back up with a Friday match after Kelly had played in the NSW under 20s Origin side on the Wednesday.
Woolf thought Kelly could do with a reduced workload in the centres and Brimson had begun to be targeted defensively to tire his running game at five-eighth, so he moved him to the back.
It proved a masterstroke. Brimson was outstanding and finished the season there before returning to the halves last season and being co-player of the year in the Titans' last under-20s side with Moeaki Fotuaika.
"Playing fullback also took the responsibility of organising the team away from AJ and his decision-making is easier at fullback which I think helped him," Woolf said.
After a strong start to this season in the halves for Tweed Heads Seagulls in the Intrust Super Cup, coached by Woolf, Brimson's form started to wane so Woolf made the switch to fullback again.
AJ's form was A1 after the switch, leading Garth Brennan to elevate him to the Titans side for round 11. The rest, as they say, has become rookie history.
Brimson's first experience at the back at NRL level was an eye opener. Other than running strongly, in the first half against Penrith he made a try-saver on Dean Whare on the left then hared across field in the next play and stopped Viliame Kikau scoring. In the second half, his crashing tackle of Waqa Blake over the sideline to save another try was one of the plays of the round.
"I really enjoy fullback, it's such a fun position," Brimson said afterwards, obviously hinting fullback would be his preference.
"It's a hard position in the top grade but I'd love to be a fullback … or half… going forward, whatever suits the team. I still have a lot to work on in that position as I haven't played too many games there."
And his friendship with his roommate in Darwin?
"Yeah, we keep in touch on social media and I've watched his career closely of course. He's a freakish talent but really down to earth."