system
Given the following post, respond as if you're commenting on Reddit:
human
[Back to the Future] Why was a high school kid hanging out with a weird, middle-aged scientist to begin with?
gpt
Marty McFly didn't have a great life growing up. The family was poor, poorly motivated and Marty generally had to make his own way in the world, with little guidance or input from his parents. His father was a timid and somewhat pathetic man, not able to stand up to his boss, let alone give moral guidance to his children. Incidents like setting the run on fire when he was eight only show that he was a problem child, crying out for attention. 

As such he spent as much time as possible out of his house, but as a troubled kid with a smart mouth, he didn't make a lot of very close friends. When Mary was thirteen or so, he had heard about "mad" Doc Brown and after being called chicken, he snuck into the Doc's house on a dare.  

Inevitably Doc caught him, but instead of being angry, he saw something in the young Marty and offered him a job, helping around the lab and feeding Einstein. Doc constantly challenged Marty, pushing him to do better in school and learn about science, something which Marty struggled with, but less so with Doc's help. Doc inspired Marty, providing a much needed role model which let the young man grow up into a better person than his own siblings, who had no such guidance. 

Over time this unlikely friendship grew, until Marty considered Doc Brown one of his closest friends. He was allowed to help more in the lab and watched as Doc sat on the edge of greatness, waiting for that one big invention that would make him world famous...