Hey there, little nonnymouse! 🙂
I waited until now to answer, because I was turning it over in my head last night. And you’re right: Dark does bare His teeth a lot.
In the mammalian branch of the animal kingdom, this is how predators respond to a perceived threat: dogs bare their teeth and growl, cats show their incisors and hiss, and chimps “grin” and shriek.
However, those are all fear responses. These creatures are afraid and try to make themselves appear more intimidating in order to neutralize the threat.
In contrast, Dark isn’t reacting to a threat; He is the threat. So, to find a better comparison, we actually have to look at another branch of the animal kingdom.
Specifically, the Carcharodon carcharias, better known as the great white shark.
The great white has no natural predators, though it may occasionally come into conflict with a killer whale over a food source. The great white has multiple rows of knife-sharp teeth that are constantly growing and replacing the old sets. This better enables it to tear into and shred its prey… but also prevents it from closing its mouth completely, resulting in its trademark toothy “smile”.
Unlike other species, the great white has not changed much during the course of millions of years. Its position as an apex predator remains uncontested, and it has never had a need to evolve like the species below it have.
Markiplier has already gone on record stating that the form of Dark that we see is really a “human suit” being essentially used as a puppet on a string. Meaning, we don’t know what Dark really looks like, what He truly is… but the movements of the “puppet” are consistent with something that’s not remotely human. Something that, if it were part of the natural world, would be sitting pretty at the top of the food chain.
Who wants to bet His True Form has one killer smile?