The chaos beast within
Aatxes come from the underworld, I assume this is the reason for the link with Necromancers.
I think they’re just the soul of a person. They share the same model as a shade and a shade is a soul of a dead person. A chaos beast is just the soul forcefully ripped out, which is really dark if you think about it. The body disintegrates and the soul is forcefully ripped out. There isnt even a trace of the body left and then you kill the soul just causing that person to vanish forever.
sigh wrote up a response, forums log me off for some reason, lost the write up. :/
Anyways, let’s see if I can repeat it all…
In GW1, Aatxes were considered Nightmares (and in GW2, Aatxes, Shades, and the Shadow Behemoth are counted the same kind of race), which while the lore on them was scarce and well hidden, in Xandra’s quest Hunted, Xandra calls nightmares named after negative emotions (similar to ritualist bound spirits) spirits themselves, and the Vaettir (nightmares in the Far Shiverpeaks) often were at graveyards and abandoned homesteads. Aatxes were native to the Underworld, the Realm of the Dead, on top of this.
In GW2, this seems to carry over. Aatxes, Shades, and the Shadowbehemoth come from the Underworld in the wilderness, and in Iron Marches, Bria’s Shadow Fiends inhabit the bodies of local charr after their souls were displaced, furthering this theme.
So Shades – and by extension, Chaos Beasts, especially in the skritt’s case – appear to be generic hostile spirits. Necromancers summoning them is an extension of them delving into the spiritual (see their spectral skills), almost making them a mixture of necromancers and ritualists (though still heavily leaning on the necromancer side – which in fact resembles their original lore for Tyrian and Elonian necromancers far more than the GW1 necromancer mechanics did).
Stop treating GW2 as a single story. Each Season and expansion should be their own story.
As far as I recall, Necromancers summon shades, not chaos beasts. :P