In this world your soulmate's symbol is a mirror image of your own, placed on the opposite side of their body and meant to line up perfectly when pressed together. Sometimes people's markings are on their wrists or their palms, the kinds of places that touch when shaking hands for the first time. Other people's have their marks on their chests, aligned together for the perfect embrace.
Derek's mark is on the side of his neck. A triskelion inside an enneagram – the mark of his family, and a model of the human psyche. He's not sure why the universe thinks he's a good match for the small, sarcastic (wonderful, perfect) human who shares his mark, but it's hard to fight against destiny.
Soul marks are meant to line up perfectly when they touch, which means they're always perfect mirror images of one another. The soulmates themselves, however, are not.
Two - Thoughtful Acceptance
Soulmates are supposed to be perfect for one another, so says the universe. That doesn't stop anyone from sometimes feeling insecure or wondering why exactly the universe chose you of all people to be forever entwined with someone so much more special than you are.
Three - Perfect Contentment
That feeling when everything comes together and you finally feel like maybe this happiness is something you can have forever.
Merry Christmas, @kaidarknight!
I tried to write something, I really did. But then I got distracted with art, so that's what you get. Three illustrations in which Stiles and Derek are (unlikely?) soulmates who (naturally) each think the universe must have been mistaken to pair someone like them up with such an amazing person.