Why did Atreus become Pantheon? (Not a troll post I promise, legit question)
Pantheon before the rewrite was known as Pantheon for the same reason my mother's name is Athena, a name's a name. For mortal matters, it doesn't really matter, it's more the implication of certain traits your parents wanted to be present in you if they choose a specific name for said qualities, like Michael with the thought of loyalty and strength ala St. Michael the Archangel, or Sarah in honor of your grandmother or so on.
The rules change when you apply them to gods and pseudo-godlike beings.
If his name was Achilles, it'd be random but okay, sure. Pantheon means "all the gods of a people or religion collectively," and Atreus ascended and became "Pantheon". Does that mean he is another Legion, an entire pantheon of Rakkor's war gods embodied in a single vessel ala Kalista, Udyr or whoever hosts more than one soul within themselves? Is Pantheon a single entity, a singular god-like being who is the aspect of war? If he is the latter, why is his name Pantheon outside of recognition then, as it doesn't make sense when you give the context that gods and the divine work in specific way. Ares is the God of War, singular. The Furies are multiple beings and are collectively known as "The Furies", plural.
If it's the former, will we expect to see a VO representing Pantheon's multiple war-like facets now?