Disclaimer: I do not own Warhammer 40k or related properties.
The Astral Hawks have no listed canon information save their Chapter symbol and armour's color scheme. All of this is artistic license.
"You must focus all of yourself!" Steel hits steel with a ringing clang and the morning sunlight makes it glow like fire. "No distractions!"
A fist enters soft abdominal flesh with a whump and a crack. A man that is more than a man drops to his knees. A dagger falls from his hands. His head hangs in shame as he catches the reflection of his own gaze in the blade. The eyes are bluer than any sky and twice as deep.
Rough hands grasp his shoulders and pull him to his feet. He does not look up.
"You are too quick to hesitate. Your movements indicate contemplation, which is vital, but you refuse to obey instinct when it comes. Sometimes we must trust our own body to take care of itself." The voice is not condescending nor kind. It speaks what it has seen as it has seen it. Still his head does not raise. He is shamed. He will fast again, this time for six days. Perhaps then he will remember not to think.
"Brother." The voice holds his discarded dagger by the blade so its grip points at his chest. "Again."
He takes the dagger and sets his chin. His opponent watches him with eyes as blue as his own, but their depth is not nearly as vast. He slides into the ready stance and feels his broken rib settle. Again.
And again. And again. He is beaten every time. His blood makes slick the floor when his opponent calls time. He follows the victor from the blade room like a servant after his master. He must remember not to think.
He passes his brothers but cannot see the looks they give him. His gaze has been lowered to focus on the heels of his mentor. Left. Right. Left. He must not think.
He sits still as the Apothecary sets his ribs and stitches his wounds. The needle pulls at his skin and he winces. The smell of antiseptic seeps into him. How many cleansing rituals will be required to remove the scent? He stops. He must not think.
Sweat drips into his eyes. The noonday sun is hot, but his armour's cooling system is strong. It is also heavy. Rocks crumble under his fingers and drop into the clouds below. The fortress of the Astral Hawks is still two hundred feet above him. He must not think.
He has returned to the blade room and sits on a clean floor. The scrape of the whetstone on his dagger fills his mind. The moonlight makes the blade shine behind his reflection. His eyes are bluer than any sky and just as deep.
He stands at the edge, just outside the fortress's walls. The sun fixes its gaze on him through thin wisps of condensation that float on the weakest whisper of a breeze. His mentor says this is perfect weather for his first jump. The jump pack is heavy. Heavier even than his armour. It pulls at his back like it wants him to back away from the cliff. He does not look down. He must not look down. To look down would be to think of falling and he must not think.
He sees only the sky and feels the drop and then his jump pack is no longer heavy. He does not think.
His feet connect with stone. His mentor claps him on the shoulder. He takes his helmet off to breathe. He looks down only once. In the reflection of the eye lenses, he sees himself. His eyes are bluer than any sky and not quite as deep.
He no longer thinks. He cannot remember how many times he has jumped nor how many enemies have fallen under him. His body knows what it must do. He jumps and he kills. To think is to fear, and he does not think.
A crack. The sky is an opal blue. Above him is the morning sun. Behind him there is fire. He sees other Marines in flight, but the sky does not want him. His jump pack is no longer heavy. He is falling, and realizes there is not much left for him to do but think.
This is his last flight.
He cannot remember how old he is.
He is proud of his Chapter.
Will he finally meet the God-Emperor?
He will miss his brothers.
At last, he does not think.
The sun sets on a field of battle. Marines clad in black and blue power armour collect the corpses who are marked by a white hawk on a red base. They do not think. Fallen Astartes are piled like discarded supplies in a transport. Onto the ship is stacked the body of a Marine whose jump pack has been smashed through his spine and fits neatly inside his ribcage. The head tilts back as it is carried. A helmet slips free, greased from the inside by blood.
The eyes are bluer than any sky and twice as deep.