Did you ever wonder how Marty McFly, teenage cool guy, and Doc Brown, looney mad scientist, became friends? I mean, seriously, an old white-haired guy and a skateboarding teen? Well, according to the co-creator of BTTF, it's because of young Marty.
Bob Gale, co-creator of the BTTF series, explained the origins of Marty and Doc's friendship as this:
For years, Marty was told that Doc Brown was dangerous, a crackpot, a lunatic. So, being a red-blooded American teenage boy, age 13 or 14, he decided to find out just why this guy was so dangerous. Marty snuck into Doc's lab, and was fascinated by all the cool stuff that was there. when Doc found him there, he was delighted to find that Marty thought he was cool and accepted him for what he was. Both of them were the black sheep in their respective environments. Doc gave Marty a part-time job to help with experiments, tend to the lab, tend to the dog, etc.
I believe it! Even though Doc wasn't cool per se, he made science look damn cool with all the bat shit crazy things he tried to pull off. Any 13-year-old would have loved to work with him. [Mental Floss]