After the horrifying events of Stranger Things Season 1, one would think that the townsfolk of Hawkins, Indiana would show extra caution around anything that could be paranormal or supernatural. But D'Artagnan (or Dart) on Stranger Things proves that sometimes even the most logical people can be swayed by cuteness. Spoilers! After finding a small, slimy creature in his garbage bin, Dustin gives it food, shelter and even a name. However, not knowing what Dart is or where he comes from could prove to have major consequences for not just Dustin, but all of Hawkins.
D'artagnan is a name that Dustin bestows on his new trashcan friend that's inspired by their mutual love of the candy bar Three Musketeers. (D'artagnan is a major character from the novel The Three Musketeers.) However, a fondness for nougat isn't the only odd thing about this mysterious creature. Dart appears to be reptilian but unlike Dustin's turtle, Dart can't stand the heat. Dustin's plan to show this creature to Mr. Clarke, his teacher, is soon de-railed when his friends come to a shocking realization. There's a reason that none of them have ever seen a creature like Dart before, and it's because Dart isn't a creature from Earth. He's from the Upside Down.
At the end of Season 1, it seems that Will Byers' life is about to go back to normal. After spending a few days in the Upside Down, he's reunited with his family and hanging out with his friends once again. Until he goes to the bathroom and begins coughing. Out of his mouth flies a small slug-like creature — one that looks suspiciously like Dart. It looks like whatever birthed Dart used Will to transport this mysterious creature to the real world, only for him to turn up in Dustin's trash can nearly a year later. While D'art begins his life as a seemingly harmless small animal, things begin to change once he's taken into Dustin's care.
After taking care of Dart for about a day, Dustin notices that he's started to grow at an extremely fast rate. One day it's a tiny slug, and the next it is growing extra legs and eating Dustin's cats. It doesn't take long for Dart's appetite to grow beyond 3 Musketeers bars, and soon the little guy manages to escape. While Dart's growth is frightening, the most terrifying part of it is its mouth, which looks exactly like the mouth of the Demogorgon.
As if a dog-sized with the face of the Demogorgon isn't scary enough, an attempt to hunt it down goes horribly awry when it is revealed that these Dart isn't just growing larger — it's also multiplying. A showdown with a bat-wielding Steve Harrington turns into an ambush as Dart and two identical creatures circle him before being mysteriously called away. Dart may be cute, but it's also deadly.
These "demodogs", as Dustin refers to them, all seem to share a thought pattern and follow the instructions of a larger force. By the end of Stranger Things Season 2, there are more than a few casualties as a result of the demodogs – mostly Hawkins Lab scientists who, frankly, should've known better. However, Dart proves that there are far more creatures than just Demogorgon roaming The Upside Down.
There's no telling what other terrifying creatures reside in this mysterious parallel dimension or how they'll attempt to sneak into the real world next. The only thing that's certain is that Dustin will likely think twice before trying to raise another brand new species that he finds in his trash can... without consulting a scientific authority.