left behind from kids fun before us

What if… by the age of 16, Steve McGarrett is a trained assassin for the US Navy, going on secret missions around the world but he’s always longed for more. When an op against the Hesse brothers goes awry, Steve is left behind, presumed dead. He sees it as an opportunity to lead a real life away from the military. He pretends to be an exchange student and heads to Hawaii where he stays with the family of Chin Ho Kelly and starts high school, but he doesn’t quite fit in as he’s not used to being around kids his own age who talk about things other than weaponry and tactics. He meets Danny Williams, someone who moved to Hawaii the year before and still hadn’t been able to fit in either and they have a lot of fun but Steve has his eye on Catherine, the coolest kid in school, head cheerleader and singer in a local band people say is destined to make it big.
When the Navy find out Steve is still alive (thanks to him accidentally appearing in one of Catherine’s youtube videos) they want him back. Add in the fact that Victor Hesse also saw the video and wants Steve dead, and the homecoming dance becomes a disaster.
But despite the fact that the school gym is practically razed as two sides fought and Steve had to save everyone, more importantly he discovers that Catherine and he have nothing in common, she doesn’t get his jokes and she’s really just interested in her own life. But Danny? He’s the one Steve finds himself wanting to impress, wanting to make sure is safe, and wants to be with.