Random prompt 2! (Patreon)

A friends to haters to frenemies to lovers trope, all in one bag hahah

it’s a generic journey story, where angel and demon actually start to reconcile and the human begins to remember their time as kids, reminiscing over their hijinks.
so it goes like this:

one day, human mercenary starts to have marks over his body, every day it grows further along his skin. till eventually it stops, and he is confronted by a demon and angel, who have matching tattoos as him, however only half of ther bodies are covered. Turns out! These were his friends when he was but a wee kid, and somehow before the demon and angel had to leave, they made a soul contract with him,  their bodies being proof of their binding. So they would never ever be apart… in an almost literal way! Their souls are now interconnected, and he was the missing piece to their contract, due to them signing with him, they inadvertently signed with each other! As They grew, the Contract grew with them, reflecting their own power. It was innocuous at first, but when the demon And angel started to hate each other, it became… more problematic.
Example! (each of the 5 senses are slowly being shared, including pain)(If one of them dies, they all die)  their distance from the human began to make them feel weary and uncomfortable, as if their souls are being stretched!  Now both the demon and angel finally agree in one thing: they need to annul this pact) but problem! How?! They came to find out that this was a forbidden incantation in s book that should no longer exist! but it has to be somewhere they think… So with the human, they all set in a journey to find the book that contained the soul contract!  So they can finally break the seal and seperate.

it was originally even simpler, just that a boy was dragged by a bickering demon and angel to remove the seals on their bodies, just cus the angel and demon can’t stand each other and the sight of their matching tattoos upset them. they realize later on that, we’ll actually this contract can’t be easily annulled, actually runs deeper than they think, and it’s a “one of us dies, we all die” scenario. Sharing senses and experiences became later in, as they become closer through their journey to break the seal. Though these differences are only minor to the main plot, the journey!