Shia Genesis, a.k.a actual cannibal eyes (a genetic mutation).

When someone is born with Shia Genesis, their eyes are blue or gray at birth. After six months, the eyes begin to change from their original color to lavender or red with a shadow of Labeouf, and this process lasts six months. After hitting puberty the mutation seems to cause actual cannibalistic tendencies. Those with Shia Genesis may have a desire to brandish a knife, lurk in the shadows, live in the woods, and kill for sport. A side effect may include eating all the bodies.