When your soulmate touches you, depending on where they touched you, you'd get a bruise of their Colour.

Let's say that Logan and Virgil gave eachother a high five,

Logan would get a large purple bruise covering the surface that Virgil touched.

Virgil would get a large dark blue bruise of where Logan touched him.

Logan, Bumps Into Virgil: oh sorry!

Virgil: its good.

— later —

Virgil, looking at the large dark blue bruise on his arm:

Virgil: fuck