Hi! So I see a lot of art of Loke with lines around the mouth, and honestly, I don't know why they are there. Have been trying to figure out why on my own, but no luck. Do you know why?
There’s a story that goes along the lines of Loki cuts Sif’s hair and Sif tells Thor to beat him to pulp and Thor tells Loki he so will do just that, unless Loki gets Sif new golden hair, right now.
So Loki finds a few dwarves, because they’re known as capable of making neat stuff quickly. He makes a bet that can only benefit Asgard, whichever way it goes - two dwarf brothers will compete against each other and whichever makes the stuff Asgard’s chief gods (Odin, Freyr and Thor) like more, wins. They would get paid well. And Loki wagers his own head because no, of course he’s not lying, he would never, how dare you.
Of course he lied, so Sif gets her hair and Odin gets a spear and Freyr gets a bunch of cool stuff, but the dwarves get nothing, really.
They finally ask for Loki’s head and every god in Asgard is like “yeah, please do”. Loki is, of course, not so taken with the idea and probably a bit insulted at that point already - like, excuse you, who got you all these new fancy treasures? The dwarves are angry that they were tricked and Loki is faced with the threat of an axe to his neck.
“I’m a man of my word, and my head is your prize, but we never said anything about my neck,” he says. The dwarves are even angrier now because they were double-tricked. One dwarf is ready to sew his mouth shut because by Hel, NO ONE wants to listen to Loki at that point.
Loki tries to run away with his magic shoes that let him walk on the sky, and Thor flings his arm around to throw his new hammer at him, after which Loki falls like a rock. The dwarf gets a needle “and its brother, Awl” to punch holes through Loki’s lips like a shoemaker, and sews his mouth shut.
Loki rips the stiches off at some point, I figure, so the lines around his mouth are scars from that. (Which is why I also didn’t draw them on him on the young version, just creating the world.)
The story is told in Snorri’s Edda in its entirety. The idea of scars around the mouth is also why it’s thought that the Snaptun Stone is an image of Loki.