Hello! Some time ago there were two races posted on the forum, the Savrix and the Wel'tran who inspired me then to make a promise to post a xenos race of my own that threatens the Calixi Sector, and without further due here is the first draft of it. I'm starting with the fluff and then we'll get down to the crunchy parts. 
Also forgive crappy English and poor proof reading as I'm writing an essay which takes alot of time and energy. 
The Feras (sing. Fera)
The Feras are known in the outskirts of the Calixis sector and in the Koronouse Expanse as a creeping dread and hidden death. Already Imperial forces have clashed with these aliens on a dozen planets across the sector and the predatory warfare waged by the xenos have left their mark on the guardsmen facing them while at the same time Rogue Traders can tell of dealing with the race as mercenaries for at least a century in the Koronus Expanse. There is a fear that the engagements so far have only been a few blips caught on the radar and that the Feras have infiltrated Imperial planets to a much higher degree than imagined and could have some sinister connection to the Tyrant Star as they seem to appear on many worlds which have suffered the “grace” of the Tyrant Star.
Physical Description
The Feras are humanoid standing at about 1,8 meters height at average for males and 1,6-1,5 meters for females. Both genders are lean in built and muscled with two powerful hindquarter legs for running and long jumps but disadvantages in some terrain. They have two arms, a short neck and re-production that organs looks very much like human ones with some exceptions although the females are flat-chested until pregnancy. The creature has only limited body hair in the form of a short but course black fur on the back which also extends to the legs and arms, males have a thicker growth than females. The skin is dark grey- dark green in color.
The faces and heads are shaped similar to a Terran wolf’s with a snout and a mouth of big fangs ready to tear and main a prey. The creature has two yellow eyes with slit pupils and a very good night vision that won’t let it see in perfect darkness but see very clear with very little light.
Arms and hands are like humans with opposable tums although the Feras also have great and powerful talons which can rend and tear. These talons can be drawn inside like a cat can and so the Feras are still able to engage in delicate operations and manipulations of objects when desired or avoid harming something by mistake.
The race is a carnivorous but seems to be able to eat vegetable consumables as well if needed but its not a favored source of nutrition. Their voices are deep and loud and they can howl loud enough to be heard for kilometers away. All five senses are very well developed as appropriate for an apex predator.
Male and female differences are very much according to the same pattern as the human gender differences; males have a somewhat more muscular build and aggressive nature than females for example.
Top natural age appears to be about 60 years and while the race shows remarkable regeneration ability in their youth that starts to decline towards 40 years or so and at 50 years they heal no better than a human and most Fera who die of old age does so from damaged organs or accidents that won’t heal. Implants can help but there is no living Fera at present who have lived over a century
History
The early history of the race is shrouded in darkness and much due to loss of said history. What the Feras know is that their race was once the masters of a pocket empire of some worlds and that it was a golden age. At that time they lived on a slave-prey caste of humans from who they directed to what projects they desired and then took what they wanted and were worshipped as dreaded gods by the slaves who sought to appease them.
The end came when the Feras captured slaves from the Yu’vath who brought the worship of Chaos into the empire and huge numbers of the slaves embraced it over their xenos gods and even some Fera took to it. The long series of bitter wars that followed more or less destroyed the slave caste and decimated the Feras who were close to extinction before they violently purged the Chaos taint from their ranks after laying low the corrupted humans and the Yu’vaths. While the home planet of the races was undiscovered most of the planets they had previously inhabited were cleansed by the Angevin Crusade in the wake of the civil war, which may actually have allowed the race to survive as the humans only thought of it as very weak race to be effortlessly exterminated and so put no energy into finding their source.
After the war only vestiges of the former knowledge remained in the care of the Feras lodges but most of their civilization returned to a much more primitive state of hunter-gatherers and returned in force to the religion of their ancestors which had almost been marginalized in earlier more hybris-filled years – the worship of the Tyrant Star.
The next great change came with the arrival of an unknown Rogue Trader, who the Feras calls the Ferryman of the Void, who in return for certain objects that the Feras placed no value on agreed to ferry the Feras between the stars and take some wit him. Its turned to be a mistake by the Rogue Trader when the Feras turned on him and either slew or enslaved the crew and used the vessel to travel across the outskirts of the Calixis Sector and sneak into the Koronus Expanse. Here they re-learned of the greater galaxy and their place in it and made contact with both xenophile captains and the Stryxis.
Since that time the Feras has spent much time as mercenaries for various groups in the distant Koronous Expanse in return for advanced weaponry and started to learn about the area of space near them. In recent times the thoughts of recreating their lost empire and the zeal of their faith has caused them to take more active actions, like capturing and enslaving Chartisan ships for the purpose of allowing them to reach new world, where they can re-create a version of their empire of old. Much of this mobility has been possible with either enslaved crews or by paying xenophile Rogue Traders to take them between the Calixis Sector and the Koronus Expanse.
Society
The basic part of the Fera society is the pack, of between three or five members to dozens of individuals under the leadership of an alpha, who is the pack’s most powerful warrior as such things are decided in duels of arms. The packs are the basic economic, political, military and social unite of the race and as such is also revered and highly celebrated. As far as human observations and investigations have shown there has been little of what humans would recognize as gender roles. While trans-pack communication happens a great deal most social energy is invested in the pack.
These packs interacts with each other according to a pseudo-feudal system where different packs have made oaths toward each other and where larger packs can let out part of their territory to other packs in return for support when requested. In general there is little subtle about Fera politics and it usually comes down to bloodshed in savage guerilla warfare between the packs involved and what allies and vassals they can summon. Personal disputes are settled with one-on-one duels which are often to the death.
The secondary part of society is the lodge which is in effect a group of Feras, also from different packs, who have come together as a fraternity or a sorority to practice or maintain a specific knowledge, technique or skill. The most common ones are those devoted to a piece of technology maintained from the past times or some kind of warrior fraternity which celebrates the use of a specific weapon or way of fighting.
Psykers have an interesting position in the society as they are both feared as potential gateways for daemons but at the same time considered blessed for better than any Fera they dream the Star Dream. Mostly psykers are kept apart and form their own isolated lodges in far off places to which packs or single warriors can travel to hear their guidance in various questions. If psykers shows signs of chaotic influence they are kill out of hand although other types of madness, such as the one from the Tyrant Star, is revered. More than any other psykers can go on a pilgrimage in order to find the Tyrant Star and sometimes with a following of other Feras coming along in the hunt for glory.
In regards to the slaves the system is both relatively simple and very brutal. The Fera cares little for their slaves who they can always replace and when they need something they summon their slaves and shows what they want to be done. Those who can deliver what they want are rewarded while those who fail or don’t show up are deemed expandable. The expandable ones are used as a food and the targets of cruel games played like a cat plays with a mouse. While brutal however the Feras knew that common men with no equipment could not build a plasma pistol and so the raiding Feras were as interested in stealing equipment and machines as abducting slaves of different sorts to support their system. This is a way of operations which they have returned to in recent times.
Culture
The basis for the Fera culture seems to be the pack, dominance and submission and the right by might attitude to most things. Defeated parties can accept harsh treatment or humiliation due to the understanding that it is the stronger parts right to do it.
The religion of the Feras have no organization like the Imperial Creed but each Fera stands before he god although the alpha of a pack is often a kind of semi-priest. The closest things that the Feras have to priests are the psykers but even then they are more of seers or soothsayers than priests as humans imagine them. The focus of the faith is the Tyrant Star which interacts with the Fera through Star Dreams where the Tyrant Star shows maddening visions of its terrible glory and calls the Fera to come to it and see its dark wonder. The Fera thinks that the Tyrant Star is their god and maker manifested who will deliver the entire sector into their hands to rule and to bask in its black light will bless them beyond mortal imagination. So far no Fera have managed to stand on a planet above which the Tyrant Star has appeared and so that hypnotizes has yet to be proved although the Fera feverously prays for the Tyrant Star to appear above their world and bless them so they may go forth and remake their empire again.
In daily life the Tyrant Star is a distant god who calls to its “children” as the Feras calls themselves, and religion is mostly about making themselves ready to be blessed by their god when the time comes. In the Feras beliefs the dead Feras are with the Tyrant Star and that their god will one day come to them and allow them to dominate the entire universe, which to their knowledge are the Calixis Sector and the Koronus Expanse.
The society is a warrior one where actually crafting items that are not meant for war or hunting is seen as a great shame and instead it has relied on the human slaves to craft items for their alien masters. Trade is looked down on in general as a real warrior takes what he wants from whoever happens to have it, with the exception of the creation of weapons, although some Fera have hired themselves out as mercenaries to see the galaxy and the social stigma on trade is not as strong as it used to be. Valued virtues are bravery, success in hunting and war, skill with arms, physical strength, zeal for their faith and loyalty to the pack and race and the Fera like to make their success visual for all to see how successful they are in upholding their culture’s values. Other life-forms are categorized as slaves, worthy opponents to be defeated or pests to be exterminated.
Sexual relations within the pack are, to use a human word, very, very liberal with little observable norms or regulations with the exception for that the alpha seems to have first pick and everyone else in the pack must have his approval of any union. It’s entirely possible for members of higher ranking packs to demand that non-alpha members of subservient packs are sexually available to them even while this does far from always go without friction or conflicts, blood feuds between packs have started and lasted for decades over such issues.
Occasionally a member of a pack will be exiled for one reason or another and they usually approaches other packs who might chase him off, kill him or take him in depending on to humans obscure reason but it seems some sort of test of dedication is mandatory. This mobility is how the gene pool is kept relatively fresh. Surprisingly enough most issues within the pack that can’t be resolved seems to involve that a Fera leaves the pack and looks for another one to take him in and it only goes to ritual duels when honor has been insulted.
In terms of clothing and accessories the Feras use what humans would call a tunic sewn from preys laid down by the Fera himself and adorned with tattoos of many different kinds, often connected with their faith in the Tyrant Star, and with accessories that are associated with martial power, like teeth from large predators hunted by the Fera. When going to war or hunting the Fera usually remves their tunic and so wears only a loincloth and whatever armor they may have for increased agility and to show their bravery.
Technology
The Fera did once have a relatively advanced technology but it can never be claimed that the Fera themselves invented much of it but rather in one way or another stole items from others and forces their slaves to construct their items for them and therefor it was always a mix between various races that the Feras enslaved or raided.
What is known is that the Feras relish close combat and primarily used close combat weapons, plasma weapons and anti-vehicle explosives when at their greatest, and that they infused their physical power with implants and limited gene-manipulation. At present they are only really capable of creating new weapons like spears, swords, wrist blades, javelins etc. and so the more advanced plasma or power weapons in their possession are prized relics that the Feras will go to almost any length to protect or recover. Hence while the Fera packs usually have a core of different primitive weapons they also use what local items that they can get their hands on and learn to use which for the most part tends to be of human design.
In terms of civilian technology the race never saw much value in that and instead opted to live hard lives so not to grow weak and so did never bothered to make their slaves produce anything in that area for them. Capture ships from other races, mostly humans of the Calyx Expanses was their most common source of transportation and often operated by descendants from the enslaved crews themselves.
For now I'll stick with that they want to re-create their old empire.