Shawn Mendes my best friend?

Sienna Chambers was horribly bullied as a kid and still is to this day, she probably wouldn't even be here if it wasn't for the support from her best friend Shawn Mendes. But sadly he moved when they were 13 years old. What happens when Sienna moves and her and Shawn reunite will they become best friends again?, more than best friends? or neither?