Freddy, Daphne, and Velma are super keen on monsters, chasing bad guys, and all around mystery solving. Shaggy and Scooby, not so much. They’re afraid of everything and seem like they would rather sit in the van and eat sandwiches. So why do Shag and Scoob hang out with these mystery dorks who travel the country in search of spooky happenings?
My theory is the van, known as The Mystery Machine, actually belongs to Shaggy. We’ve all accepted that Shaggy is your typical 60’s hippie pot head. So it would make perfect sense for him to have a van decked out in wild colors and psychedelic flowers. He got this van so he and his dog could get blazed and eat sandwiches away from the judgmental glares of the squares.
Meanwhile, Fred, Daphne, and Velma probably solved some minor incident that involved the school librarian scaring the kids out of the library so she could use the place for some deviant sex cult. The rush of unmasking the fiend sparked a desire in the three to travel the country to investigate strange happenings. Their only setback was lack of transportation. But maybe they could convince the local burnout to let them use the van.
Velma kind of knew Shaggy. Some six degrees of separation thing like he sold some pills to her friend at a party once, or he dated her cousin for a week in 10th grade. So she is given the task of asking if they can use his van. Shaggy seems like a chill dude so it probably didn’t take much for him to agree to it. He also probably didn’t fully understand what they were going to do.
So they roll up on their first mystery. Shaggy has no idea it’s a mystery or really what’s going on. He just knows he has some new friends who drive him around while he and his dog toke up in the back. Occasionally they give him snacks. They arrive at this place and Fred, Daphne, and Velma want to investigate. Meanwhile Shaggy and Scooby just want to find anything to satisfy their munchies. They’re searching for food constantly but their also paranoid as fuck so they’re scared of everything. They’re locked in this internal eternal battle of food vs. fear.
It always end up there is no monster, Shaggy and Scooby do find food, and they pile in the van and head off to do it again. Shaggy can’t maintain any memory of what just happened so he repeats the process over and over. So while the other three are gung ho to solve these mysteries, Shaggy and Scooby are just in it for the sandwiches and may actually have been willingly kidnapped and now have a little bit of Stockholm syndrome.
Fred and Daphne don’t seem like they care about Shaggy and Scooby. Velma has a heart in general and accepts them a little more, but they’re really just being used for the van. That’s why they’re on the team despite the real lack of mystery solving desire.