Marks

Every human born with magical potential has a special birthmark on their skin, indicating their elemental affinity, among other things. This mark can include arcane symbols, and each is individual to the mage who wears it.

If a magically gifted human does not receive training, their mark will fade subtly over time, until the time when a mage would normally bind a familiar (sometime around seventeen years), when it disappears altogether. After this point, it is impossible for the human to be trained to use their magic, and it will lie dormant for the rest of their lives.