2Prompt Four
The eyes are the windows to a person's soul.
All Wizarding folk are born with eyes that can change between two colours: natural eye colour reflecting one's inheritance, and magical eye colour reflecting one's soul. Some witches and wizards are born with heterochromia.
Magical heterochromia is common amongst identical twins, and describes the phenomenon of twins having ordinary natural eye colour, but mismatched magical eye colour, with one eye reflecting their own soul colour, the other eye reflecting their twin's soul colour. This means that the twins have a magical bond.
Harry Potter is born with hazel green eyes and dark hair. The first time he uses accidental magic, his eyes changed from soft hazel green to piercing bright emerald, the colour of the Killing Curse, the colour of Death.
But then that Fateful Night happened. And Harry developed physical heterochromia, where the eye below the lightning-bolt-scar had changed to a dark blueish gray, like the colour of a stormy sky. All who saw it thought that it was due to physical trauma to the eye due to the Killing Curse.
Until the day he became so angry that his magic lashed out, and his blue-gray and hazel-green eyes flashed wine-blood and emerald-forest.
Eyes are the windows to a person's soul. And Harry has two.
