THE WAR ON TERRA FORCES -
"Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying."
Arthur C. Clarke
The Gray's planet of origin was Nilus in the HR 9038 B star system located in the Cepheus Sector. Once their technology had advanced to the point where interplanetary exploration was possible they spread throughout the Sector to settle many celestial bodies in the Gamma Cephei and Alderamin star systems.
Their explorations were halted after several violent encounters with the Haraka led them to retreat back to safer grounds and shroud themselves from further discovery by any future Haraka incursions, as well as any other lifeforms that might cross their path.
Some unsanctioned exploratory missions continued, including several visitations to the Helius sector with numerous unconfirmed reports of contact with Humans during earlier stages of development.
Later intrusions into the Sector by the Talus led to more savage interactions, and forced the Grays to take a more offensive stance in order to protect themselves.
ATTACHMENTS & WEAPONRY
The Grays evolved convergently over thousands of years to arrive at the three, analogously appearing yet vastly different, 'casts' that make up their fighting forces.
The smaller 'Nilayan' Grays are the grunts of the alien force making up the majority of their number and wielding much lighter common weaponry.
The largest 'Eridiyan' Grays provide the 'muscle' within the force being far more physically imposing and well trained, allowing them to wield a wider array of both standard and far more powerful weaponry.
The final 'cast' are made up of the rarest 'Alpheyan' Grays. Being the most intelligent Gray 'cast' they form the command element of the force, taking control of battle tactics and strategic planning.
The Grays arsenal consists of fewer choices than that of the Humans, however each weapon is adapted for and designed to be very tactic specific. Typically their weapons are not as strong as other Forces but have a good mid to long range, allowing them to engage the enemy before they can return fire.
The Gray force has 9 separate and distinct factions. Most Human factions arose due to their physical location, and while this is in part also true of the Grays, the different factions are a better indication of their intended purpose as opposed to where they are normally based.
Learn more about the Gray factions HERE.