Disclaimer: there are some spoilers in the article!
Among the crowd of 18-34-year-olds (so-called "millennials"), "Riverdale" has become increasingly popular since its Season 2 premiere on the CW. One of the reasons is because of how easy it is to watch. However, this does not entirely explain the reason why it has become so popular. Other CW shows that have aired on Netflix such as "Jane the Virgin" and "Crazy Ex-Girlfriend" haven't had as much success with younger audiences.
Many shows on CW are also based on comic strips and superheroes, such as "The Flash," "Arrow," and "Supergirl." Like these, "Riverdale" is based on something else—in this case, it's the nostalgic 1950's comic strip "Archie". However, "Riverdale" has nothing to do with superheroes, at least not in the kind we're familiar with. The show is about real teens facing real problems: deciding where to go to college, relationships, death, curiosity, and financial instability. According to the creators, a direct "transplant" of the original comic to the screen was not going to be enough to sustain a series.
The combination of what many people know as the "Archie" comic with present-day realities and plot twists is a recent move to create characters that can resonate with younger audiences. For example, the plot line of Season 1 follows Archie Andrews, Betty Cooper, Veronica Lodge, Kevin Keller (who happens to be gay), Jughead Jones, and Cheryl Blossom as they unravel the mystery of who killed Cheryl's brother Jason on the Fourth of July the summer before. By combining the genres of innocent happy-go-lucky teenagers with hardcore and cold-blooded mystery, the show has become something that all people, regardless of age, can get sucked into.
By adding complex characters who symbolize standardized stereotypes, the show also creates complex relationships between unexpected people. For example, in the first episode, we find out that Archie is in love with Ms. Grundy, the school music teacher. Things start to get complicated (not that they weren't already) when Archie realizes that he and Ms. Grundy were making out at the same time and place where Jason Blossom was (presumably) killed. I won't give anything else away, but at that point, everything starts to spiral out of control.
Based on that, it's no surprise that the show is coming up on its third season. Netflix recently made an agreement with the CW network that states that about seven to eight days after a show's season finale, Netflix can add it to their catalog. This agreement has made cable tv shows that much more accessible to fans, who have already made "Riverdale" one of the most viewed shows on the CW network. In addition to it being easy to access, it's also very easy to get "sucked into", as described below.
"The result reflects reality just enough to draw viewers into pure fantasy."
I love this quote because it asks the viewer the "if" question. The beginning of the first season draws us in by giving us characters that reflect our general reality. This way, it makes it seem like the things in the show could actually be possible. That's what draws the viewer in.