A tiny ray of happiness and sunshine pierced the veil of doom and gloom in Hawkins, Indiana — if only for a while. Spoilers ahead! But is D'artagnan (Dart) a baby demogorgon on Stranger Things? Early in Stranger Things 2, Dustin finds a small, frog-like creature in his trash can. He names him D'artagnan and evicts his turtle from the tank in his bedroom in order to give him a home. Dart is cute (or as cute as a slimy thing with a mouth can be) and for the moment, seemingly harmless. But, to Dustin's dismay, things go very south very quickly. It seems that Dart wasn't just a weird amphibian who posted up in Dustin's home — he's actually from the Upside Down — and isn't that unlike a demogorgon himself.
Dart gets continuously larger as the season goes on. He outgrows the measly tank Dustin originally placed him in, and he becomes more and more worrisome. He gets loose in Hawkins Middle School at one point, and Mike, Will and Lucas help Dustin find him, likely with the intent to get rid of him, since he causes more trouble every day, and they're starting to realize he must've come from the Upside Down. Dustin finds him, but doesn't tell the rest of the boys that he's taking him back home — he's become attached.
He keeps him at home until Dart reaches roughly the size of a small dog. Dustin graduates from feeding him chocolate and nougat to tossing him lunch meat from afar to save his own skin. Things finally come to a head when Dustin discovers Dart eating his cat. Yes, there is a cat casualty this season. It becomes clear that Dart isn't fit to be a pet, and Dustin's now pretty freaked out by him. He even calls him a demogorgon himself.
Dart is extremely like the demogorgon we met in Season 1. His mouth opens up like a tulip blooming, much like last season's Demogorgon, even though the many rows of teeth and unnaturally wide mouth are probably too horrifying to truly fit a flower analogy. He's obviously wriggled his way out of the Upside Down, as he is clearly not of this world, but there are some differences between Dart and last season's monster. For one, there are more than one of Dart. While Dart happened to make his way into Dustin's path, the group encounters far more of these dog-like monsters toward the end of the season. Dustin appropriately deems them "demodogs" — part demogorgon, part dog.
With the help of Steve (who redeems himself magnificently as more than just a staggeringly well-groomed bro this season, I might add) Dustin and company attempt to lure Dart into the junkyard, which is where they learn that Dart has friends. They escape for a while, but Dustin meets his old friend again as the gang roam the tunnels. He hits up Dart's old soft spot for Three Musketeers bars, allowing him and his friends to safely pass by him while he's distracted by snacking. It makes you hope, for Dustin's sake, that maybe Dart is a little more intelligent than just a mindless, murdering machine. Maybe he does recognize Dustin, even a little bit. But most likely, he's just really into nougat.
In the end, Dart is a casualty of Eleven closing up the tear between the Upside Down and the real world. After she does that, dead demodogs are falling left and right, apparently drained of their lifeforce and their power. It's clear that though the demodogs weren't exactly the same as demogorgon we saw last season, the realm from which they came must be pretty good at spawning horrifying creatures.
The Upside Down is still very much alive at the end of the season, so when Stranger Things inevitably comes back for another, perhaps we'll be Dart's counterparts will make an appearance. Though, hopefully this time Dustin doesn't try to domesticate them.