soulmates, at the three of 3 to 16 experience changes regarding their potential soulmates, they either receive a mark/writing on their body, if you have the mark, your soulmates mark will match your, if you have a writing, whatever is written is what your soulmates first words to you will be, others, 16+ will experience physical changes, example, they will get their soulmates quirk/hair color/language/or special ability

during the USJ attack in season 1