New thoughts on the supposed mascot trio!
Xerneas is representative of the life of the world, and mortality.
Yveltal is representative of heaven (it's not always diamond rings and angel wings, hunty), and the afterlife
Z could potentially represent death, or a state of decay.
Right now I'm thinking kind of an Olympos thing where there's Zeus of the heavens, Poseidon of the sea (70% of earth as it is) and Hades who has a frightening appearance to mortals, and is revered as the god of death.
Serving up shade since it was relevant.
Nothing ever breaks except for my spirit, and even that much is self-inflicted.