He has already left his mark on the game with 29 NCAA records, making him the most prolific passer in college football history. He also led the Warriors to the Sugar Bowl.
For Brennan, it's never been about records. All he wanted was an opportunity to prove himself. He's done that to a point, but never on a stage so big, with a nation watching and with so much at stake.
"I look back, and it's crazy how much success I've had," Brennan said before Tuesday night's bowl. "I realize that you're only good as your last game, and my last game happens to be Sugar Bowl against one of the best teams in the country. This game has a huge impact on how I'll be remembered and how my career will be looked at."
Brennan has gone from ex-con to Hawaii hero in his storied career.
He's Hawaii's biggest sporting icon and ambassador since Duke Kahanamoku, an Olympic gold medal swimmer and surfing star.
"He's a rock star in Hawaii," Warriors defensive coordinator Greg McMackin said.
It's not necessarily the 23 victories Brennan has racked up in the past two seasons that made him a star. It's how Brennan has won by overcoming tremendous challenges, even when things looked grim, on the football field and in his personal life.
As a freshman at the University of Colorado, he was kicked off the football team after a woman made accusations against him. Brennan was convicted of burglary and trespass for not leaving her dorm promptly and was sentenced to seven days in the Boulder County jail. Sexual assault charges were dismissed.
Brennan is still haunted, which prevented him from fully relishing his Sugar Bowl experience.
"That whole situation in Colorado has left me numb for a long time. It's hard to feel now, which is a good thing and bad thing," he said. "It's easy to block out negativity. It's easy to block out the bad things, but it's harder to enjoy the good things."
Brennan is humble, unafraid to speak the truth and has been tremendous for youths in Hawaii. While he's often called a role model, he notes that he also carries another title.
"I'm a convicted felon," said Brennan, whose probation ended Dec. 16.