Native to the deepest trenches of Europa, the Cthonians are the faction who split off upon discovering and delving deep into the use of mutative biotech. The Cthonians engaged in a bloody civil war with the Natives years ago, a war which they mostly won; the latter has been on the decline ever since. The Cthonians seek the Vaults to further improve their technology and hold on Europa, hoping to establish a dominant government.
Racially, the Cthonians are no longer a Race at all, even among individuals, as they are each grafted with mutations according to their professions and tastes more than lineage. Cthonians can be expected to be diverse, and generally aquatic-looking like their forebears, but little else.