Summary: Thiel summons a daemon. (Daemon Prince Guilliman AU, post-Heresy, PG-13, Guilliman/Thiel, remix of that time I wrote Marneus Calgar doing this same thing in this AU)
***
Of course they had wanted an excuse, but fear they would be too eager was half of what made them delay so long. Of course they were uncomfortable with an untested theoretical in their repertoire. Of course they wanted him back, personally.
But the price was too high, the contingencies too dangerous unless things already couldn’t get much worse. So they waited.
Now, here Chapter Master Aeonid Thiel was, the blood of the innocent staining his gauntlets as red as his helmet still was. It would have been comforting to have been one of the sacrifices–it would have been easier–but that was a foolish thought. He was the commander. By directing troops they were more than the sum of their parts, so his life did have more value than that of a line-Astartes. There were wounded who could be used instead, the deaths they would have had anyway given meaning. Practical.
He had insisted that he kill the children, though. Let this be on his head. It was his decision. He was the one who wanted this enough, personally as well as tactically. He went through with it.
Maybe someday they’d be so good at magic that they’d be able to summon a daemon without the murder of the innocent, like a fusion power plant to a barbarian tribe’s first water wheel. But in the theoretical in which they understood the metaphysics of the galaxy just then, it was unavoidable. The very fact it was wrong was what gave it the power to split apart reality. It had even been theorized it worked best when performed by someone who hated it, who wanted more than anything else not to do this, to find another way, but did it anyway, compared to someone who found it easy to justify the practical as necessary or who valued human lives little. A good man. If he had been able to call himself a good man before, which he hadn’t, he certainly couldn’t now; yet, it pained him deeply–that he could say.
It rose out of the blood and shadow, out of the battlefield where they had fought and out of the ritual slaughter that had been constructed for this purpose alone. A daemon. A primarch.
His troops felt no fear so didn’t fall back, but they watched, wide-eyed and curious, already with a wonder what was part awe and part frantic contingency planning. Thiel stood before them. He wasn’t up to trading a joke with his First Company captain or ruffling the hair of his Chief Librarian like he normally would have to put them at ease, and they knew what this moment meant to him, if the still-dripping blood hadn’t been enough to make them morose.
He found himself second-guessing himself. Was he lying to himself in wanting to believe he would instinctively know the truth, like in a fairytale? Had his transhuman memory failed him and it had always been this terrible, or had it truly changed? Had the daemon prince always been that much daemon and that little human? Had it always hurt to be near it so much, and had its growl made the earth shake? His old warding tattoos pricked with its presence, as if he hadn’t noticed he was in the presence of a daemon and needed to be informed. His Librarian had to look away quickly, her eyes bleeding.
“Aeonid Thiel,” hissed the daemon, in a voice that left fire and frost in the air at the same time. It glanced at his armour insignia, as if it needed them to remember what to call him. Not a sergeant anymore, he thought, not hysterical at all, no. “Chapter Master.”
It remembered him, then? Or it was pretending. “Lord. My primarch.”
“How long has it been?” Guilliman asked. He was staring at Thiel’s face with those blue, blue eyes, taking in details, scanning the other Marines of the Crimson Blades Strike Force. Long enough for Thiel to have aged, aged visibly despite his transhuman biology. For these young boys and girls he did not know to gain veteran studs.
“Four hundred twenty-six years,” he said. He would have counted every one even if he hadn’t had perfect recall. Longer than the Great Crusade had lasted. It had conquered the galaxy, yet it was a blink of the eye. No wonder it had fallen apart so fast, even longer ago. Such a fool the Emperor had been, and his primarch sons. They were all dead now, dead as the Crusade; the Imperials forever, the Chaos-sworn less permanently.
“Come here, Aeonid,” the daemon said, and Thiel went.
It was foolish. It was the easiest trick in the book. A daemon taking the form of what he most wanted to see, and then biting off his head. He’d seen it a hundred times before, happening to some poor, trusting fool. It was a powerful treason, and treason was a source of power. Guilliman himself hadn’t known if he would still be sane if he was called back, or if his reason would be lost to a daemon entirely in the service of the Great Powers. His First Company captain backed away slowly but pointedly, making it have to go slightly further to get to her, so she would be in a better position to assume command and coordinate a response in the event of his death from sudden but inevitable betrayal.
Yet he went, because he wanted to die that way oh so much. To have that illusion for a moment. If he was lucky, it would kill him so fast he wouldn’t even know better. If it decided to nurse more ritual power from him fully understand he had been had and dying slow, he would still treasure the minute of daydream enough to die happy.
The daemon pulled him to his chest, put an arm around him, claws scraping the armour plate of his back lightly. He was real and solid, to the extend that could be said of Warp-stuff, which was neither of those things. He smelled like ozone and like armour polish. Thiel could feel his teeth, but it was only a kiss pressed to the crown of his head. A benediction.
“For your service, for your wait,” he said solemnly. Then, teasing, “For your operational efficiency.”
He knew, with absolute certainty and clarity, that this daemon loved him. This daemon that had been Roboute Guilliman. As long as he lived, when his soul was burning in hell, as it would, this fact would still be true–a daemon loved him, really and truly.
“I feel like I could take on the galaxy all of a sudden, lord.”
“Tactical briefing. Your theoreticals.”
“We call them the Harrowing…”