Isaako is one of seven ex-Broncos in the Dolphins squad, with coach Wayne Bennett among several support staff with strong links to their new Brisbane rivals.
Friday night's clash looms as one of the biggest matches of the regular season, with the two teams topping the ladder and a sell-out crowd looming.
Isaako carries the baggage of being let go by Brisbane last March, released from his contract after signing with the Dolphins for 2023 months earlier.
It prompted him to spend six months at Gold Coast before completing his move to the 17th franchise, after growing up dreaming of playing out his entire career at Brisbane.
"I want to prove a point," Isaako, the NRL's leading point-scorer for 2023, told AAP.
"It was very disappointing. I never wanted to leave.
"But I knew I wasn't going to have a first-grade spot there with a lot of the young talent coming through and young players the club wanted to develop and play.
"I had idols that played for the club, like Alex Glenn. He was a one-club player. I wanted to follow in his footsteps.
"There were opportunities for me elsewhere. I had to think of my family, and that's what I did. The Broncos will always have a soft spot in my heart.
"There was a game I played against the Broncos when I was at the Titans and we ended up losing in the second half. But getting a win over them will be great."
Isaako is certain he is not alone in this feeling.
He has labelled Friday night's match as just as big as the new club's inaugural game against the Sydney Roosters in round one, in which he scored a double in the 28-18 win.
Dolphins bosses have also made no secret of the enormity of the contest, with chief executive Terry Reader dubbing it the battle of Brisbane and tipping it to surpass the South Sydney-Sydney Roosters rivalry.
"That's what we want to prove as a team, that we are No.1 in Brisbane," Isaako said.
"We've known from the start of the season that the Broncos game is going to be one of the biggest games.
"Being the second team in Brisbane, fighting for that podium. This week is going to be huge.
"There are players here who played for the Broncos, and obviously Wayne as well.
"I know he will definitely get us up for that game, and that cross-city rivalry is going to be huge."
Dolphins assistant coach Kristian Woolf confirmed on Wednesday that five-eighth Isaiya Katoa would play, despite the teenager missing training on Tuesday as he nursed a sore elbow.
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