Affinity

Diversity & Order: Military ships cannot destroy enemy ships, only their weapon and defence modules. +50% industry bonus in every system. Tolerant (++) trait from Endless Space 1. Has no use for food; grows with industry.

Gameplay

The immortals are meant to be industrial powerhouses. The industry bonus they get from their affinity, together with the fact that they can colonise any planet type from the start (albeit with a FIDS (or should I say IDS?) penalty), should help them grow quickly into the faction with the highest production output. Furthermore, because they are machines, they create new population rather than reproducing biologically, so food is unnecessary to them; what they need in order to increase their population is enough industrial resources (in game-mechanics terms, they ignore food from planets, buildings, etc; instead, their "food" is equal to their industry).

The Immortals are completely, utterly against the idea of destroying a lifeform; after all, they remember their origins (see description section). As such, they will never initiate a war, they will condemn anyone who initiates a war (although not too vocally, lest the warring faction turn violent against them), and they will only attempt to neutralise incoming threats by destroying their weapons modules. As a player, you could try to wage war and invade other factions' systems, but it will be extremely difficult because defending ships you neutralise only need to have their weapons modules repaired instead of the entire ships having to be rebuilt. The ability to colonise any planet type from the beginning means that you should have enough systems to have a decent science and industry output by the time factions start running out of space for their populations, so you shouldn't really need to wage war in order to win.

Description

The Alliance of Sentients was a vast civilisation which comprised many systems inhabited by many different lifeforms. The incorporation of new lifeforms into the Alliance was not always peaceful; however, its members enjoyed peace and prosperity once incorporated. With a host of species contributing to science, the Alliance advanced swiftly, and its scientific endeavours culminated in the creation of the first sentient machine: the first Immortal.

Ironically, it was the creation of the Immortals that brought about the end of the Alliance. When people no longer needed to reproduce because they could simply build more Immortals to populate newly colonised systems or make up for deaths, they stopped reproducing. Eventually, the last organic citizen of the Alliance died of old age and all that was left was the Immortals. Eager to recover the former glory of the Alliance and imbued with their creators' curiosity to meet new intelligent species and incorporate them, they have started building a new Alliance, one based on the principle of peace and order. They recognise that the grandeur of the original Alliance stemmed in no small part from the diversity of species that comprised it; xenocide is an obstacle to this grandeur.

Miscellaneous info

Physically, Immortals vary wildly in shape and physical capabilities. Each individual possesses body parts suited to its profession and hobbies, and new parts can be incorporated as easily as you can plug a new peripheral to a computer.

The first Immortal is called Gen 1. Subsequent Immortals are called Gen X Unit Y, where X is the number of the generation in which it was created and Y is an integer between 1 and the number of units created in that generation. They are machines; they have no use for pretty names.

I figured I'd throw this in here just to clarify. The Immortals weren't created as servants, but as the logical next step in the eternal quest for life extension. They were always viewed as equals, not as things, by their creators.