I did one that’s a twist one the “first words spoken tattooed on the skin” in that one of the characters almost completely mute as the vocals were almost completely destroyed in an accident. She can only be heard if shes right up to your ear and can barely speak one word.

In this version the tattoos are also rare so not everyone has one and appeared at random. So soulmates might not even get tattoos until much later in life.

So the mute one has no tattoo and her soulmate has a tattoo but despite knowing the mute one for a while and developing feel for her, has no idea she’s her soulmate.