It was a small and unimportant thing. Chain and cold metal. Sasuke had made it at the age of six and given it to Itachi with a great sunshine smile.
He wore it on his Anbu missions, to remind him of why he had to survive and make it home again.
He wore it when he annihilated his clan, to remind him of why he had to kill all but one.
He wore it when he went on missions for Akatsuki, to remind him of the death at the hands of an avenger – one day.
To Itachi it represented hope.