Name: Unknown,
Appearance: Mostly normal as long as he keeps heavily clothed. He has a torso and thinner limbs that look very much similar to a Tyranid Hormagaunt. The tips of his fingers and Morphed into Smaller but no less deadly rending Talons. His mouth is covered by a Metallic Rebreather to give the impression that he has augementic lungs and requires it to breath. But in reality it simply hides his mouth. If people were to see it he would be hunted in a second. 
His mouth is far from normal, Each cheek seems to bulge slightly. As if stuffed with something peculiar. When he opens his mouth (Which can be done to a width far beyond a normal human) he exposes a Host of Needle sharpened teeth. Both traits could plausibly be explained away as the resault of surgery save that he can also Unfold Four Impossibly long, finger like Mandibles that themselves end in Razor sharp Protrusions that are capable of Secreting a Postent mixutre of venoms and toxins from glands in his throat. He is also capable of spitting these toxins a short distance if he has to. 

His saliva is also mildly acidic, Not enough to melt through metal or power armour, but enough to melt through flak armour and flesh with relative ease. 

He also had a thinner form the the chitinous plating that a tyranid has. His is located on his back and shoulders. 

Skills: His increased strength is less than a genestealers and an astartes. But still a little more than double that of a Strong human male. This also reflects in his personal speed and reflexes which are less than a full blooded tyranids but more than a humans. 
Essentially he is a walking encylopedia on the strengths and weaknesses of the tyranids. Having the rare opportunity to 'walk a mile in their shoes' live with their traits, gangly limbs, razor filled maws and nigh insatiable hunger. He knows of the most basic primal urges that drive all Tyranids forward. How they work, what they seek, and how to overcome it and outsmart it. He was able to explore these things because he may live without the oppression of the hive mind controlling his every move. 

Background: His name and former identity were lost in during the process that made him what he was. And if the inquisitors and doctors who presided over his transformations know, they are not saying anything. Partly because He killed several of them when he was first awakened and unable to mentally control the hunger that had been brewing inside of him. Several partly digested Scientists, and further bio-graphs later. He had become what he was now.

His regime of testing became for more controlled and far more intense. He was starved and fed scraps, Pushed the the ravenous and primal edges of his hunger drive again and again until he could exert total control over himself and the urge. This si not to say it still wont effect his actions. But his odds of homicidal and cannibalistic spree's have lessened. Mostly. Couple that with being pushed beyond his enhanced physical limits. They wanted to know just how strong of a being they had created, compared next to live and captured specimens of xeno's. That is when he caught the first glimpse of the creatures he was molded from. 

Everything about him was tested and altered at genetic levels. Even the Innate supplication to the hivemind and larger tyranid forms was soon replaced with hypo indoctrination of imperial dogma. He was raised to abhor the mutant and the xeno. It was ingrained so deeply into him to hate everything the average Imperial citizen reviles, as well as the very thing they made him into. He hates the forces of chaos even though he has no recollection of fighting or even meeting a heretic. He hates the hundreds of xeno species he has never laid eyes on. He hates the traitor, who would bring down the Imperium from within. 

He hates himself and all xeno's, Hate, hate, Hate, hate. If the word was branded on every Micro-inch of his flesh it would not equal one-one hundredth of the hate he truly feels. Along with his never ending hunger this is a very dangerous combination. He was told he was made into a mutant to fight the things he hated so much.