7:49:43 [Exo - Kaisoo/Kadi]

"Soul-marks begin to appear when you are in close proximity with your soulmate and start to darken the closer you get, until they appear in black ink, marking the time at which you first lock eyes as a permanent tattoo"

Or, that story where Kyungsoo moves to away from home and he meets someone he'll never forget. (Soulmate!Au)