From the very beggining of the universe the soul of Eadar-eisimeileach that appear in the world is bounded by the red string of fate with another soul.
One of the soul is a Sealer- the person who's soul is holding a sacred weapon.
The other soul is a Holder - the person who is able to unseal and use the weapon sealed in his soulmate.
In the world where having a destined lover is common... Taehyung and Jungkook are special.