Robbie, in contrast, admits he usually writes about the focus of most teenage boys' attention: girls.
He mostly writes "dumb love songs", though his girlfriend does not mind, Robbie said.
"She's always my first audience."
At the competition Robbie performed three of his songs - Red Lips, Hold my Hand and Bob Cuts, which is about his best friend and was only written three days before. After advancing through the heats in August, he was up against six other performers from around the country in the national final.
While Robbie listens to the Beatles "24/7", he said he admires British singer-songwriter Ed Sheeran.
"The way that he has done it as one guy and has shown you shouldn't get caught up in the show business of it," Robbie said.
Sheeran's down-to-earth path to success made him someone for Robbie to aspire to.
Robbie has been performing all his life by busking, performing at festivals and as the lead singer of the band Yellow Mercury, which competed in the Northland heats of the Smokefreerockquest this year.
"I guess it's (music) sort of all I like doing," Robbie said. "It's something that I want to make a career out of and just do all the time because I love it."
Occasionally Robbie does delve into serious issues, such as a song he wrote recently about self-harm after he saw a girl on his bus with cuts on herself.
"I guess I take experiences and feelings I have and make a song about it," Robbie said. "If a person listens to it and feels a connection to it that's my job, I guess."
Robbie's teacher and head of music at Whangarei Boys' High School, Ginny Hill, said she was thrilled with Robbie's win.
"He is passionate and has commitment to his audience," Ms Hill said. "He's only too happy for perform at any occasion."
Zeal is an organisation focused on encouraging young people in arts, leadership and education.
