This would most definitely be rated M for graphic violence and language. However, no one really needs any former knowledge of Marvel's Venom or how the symbiotes work. This is inspired in part by Season 0's characterization of the Spirit of the Puzzle. Because he was a bit of a sadistic bastard in that.
Prologue: The Shadow of Horus
They dug in shifts. The heartier men worked the day, when meager tarps and canvas sheets were the only things keeping the desert sun from burning the skin off their backs. Others worked at night, guided by lamps and even torchlight in this primordial wasteland.
But now, the horizon was devouring the sun. The day men had just switched with the night men.
"This is fucking stupid," a laborer growled in English. All of the local guides left immediately. Some superstitious shit about cursed tombs or something. "Why the hell aren't we allowed to use a fucking CAT and some explosives again?"
The man next to him swung his sledge hammer. Metal clanged against sandstone. "Something about not damaging the contents of the tomb."
"Seems like a wild goose chase to me. We don't even know if we are in the right area, much less what the hell we are looking for." He grunted he swung again. They were slowly cutting into the cliff side. Key word: slowly.
"Eh, at least we are getting paid decent," the second man panted before he swung. The head of the hammer lodged itself into the rock. It echoed with a hollow thud.
The pair exchanged glances.
The first man swung. The yellow rock fractured. Tiny fissures veined out. The cracks were black. The bits of rock collapsed inward. A small black hole. The pair laughed and shoved one another.
"Hahaha, we found it!" they called to the others. Their voices rang through the desolate valley.
The others crushed in. A man even stuck his hand into the fist-sized hole. He touched cold, stale, millennia-old air. By the time the moon reached its zenith, an opening large enough for a crouched man tore into the cliff face.
A researcher nudged his way through the brutes. He held a big electric lantern in one hand and some papers tucked beneath his other arm. He was an archaeologist or Egyptologist or whatever the hell they called themselves these days. The laborers didn't care. Some even said that a true archaeologist wouldn't be some desert rat for capitalists, anyways. So it didn't matter.
He wore a face mask. No clue what sort of ancient fungi lurked in these tombs, waited for fresh lungs to decimate. The laborers followed, faces bare.
Sure enough, carvings and paintings scrawled all about.
He frowned. "The portraits of this man have no faces." He touched a carving with a gloved hand. The faces weren't scraped off by some vengeful defiler. They carved them without faces. A man could not properly travel to the afterlife without a face, or so the ancients believed. He walked close to the walls. He followed the inscriptions, which were supposed to depict the dead person's journey to the afterlife. Supposed to. But… this didn't seem like a spell for safe return to divine providence.
"Isn't there supposed to be a coffin or something?" a laborer asked.
"Sarcophagus. Yes," the researcher absent-mindedly answered.
He turned around. There were supposed to be many things. Jars of vital organs, furniture, food, valuables. But… the tomb was empty. But the walls, save for where they had just entered, were untouched.
No tomb robbers.
He looked back at the carvings.
It wasn't a tomb.
"Hey, I found something over here!"
The researcher immediately whirled. "Please refrain from touching anything yet!"
Too late. There had been a small alcove cut into the rock, shelf-like. A golden box, about the size of a child's lunch box, sat upon it. Or, at least, used to, since it was now in the grubby, sweaty mitts of some brute.
"Put that down! You don't know if it's boobytrapped!" the researcher hissed.
The men laughed. Immature. But the box was replaced upon its shelf. He cautiously approached the shelf. He investigated the walls. There were no seams, no cracks, no holes. No traps. He looked at the carvings in the small alcove.
"They refer to whatever is in this…" It wasn't a tomb. What was it? Perhaps a vault, a safe of some sort? They didn't seem to want anyone to get this box. After all, it was hardly mentioned in records. What got them this far were pale imitations of clues left in obscure text. "As the 'Shadow of Horus.'"
A laborer tapped the top of the box. "So what's in this?"
The researcher delicately lifted it up. The box itself seemed to be solid gold. It strained his arms horribly to pick it up.
"'Solve the puzzle, and obtain great and dark power,'" he read slowly. He set it back down and tried to open it. It was closed tight. He couldn't even get the lid to wiggle.
"Looks like there's something on the top," one of the laborers said.
The researcher blinked. Indeed, little gold tiles. He cautiously fingered them. They could slide. He shifted one. Something in the box clicked. He peered intently at it, nudged the lid. Nothing.
"Something on the side moved," a man said.
The researcher moved the same tile again and stared at the box's flank. Indeed, a corresponding tile shifted. He made a noise low in his throat. "I've never seen something quite like this before. Not from ancient Egypt, at least." And never something as complex as this. He cautiously lifted the box back up. "I hope this is what he was looking for."
Back in America. The boss-man decided to have the puzzle box put in a contaminant-free, airlocked environment. They could've smashed the box open. But he didn't want whatever was inside damaged.
The researcher wondered just what his boss was expecting.
With gloved hands - he had an entire stuffy rubber suit on - he prodded at and slid the tiles. Each of the little plates of solid gold had an inscription. They seemed like hieroglyphics, but they were… corrupt. Either old or some experimental language that never got its feet off the ground. He couldn't quite comprehend their meaning. It made solving the puzzle all the more difficult, and it made no sense. The inscription on the front was clearly legible Egyptian hieroglyphics.
He slid a couple more tiles around. The sides of the box clicked. He glanced at them. Each side tile corresponded with multiple tiles on the top and other side. He made a noise low in his throat.
Five months passed. His boss grew evermore impatient concerning the puzzle box and its contents.
The researcher grimaced. He worked on it alone, at night sometimes. That way his boss wasn't breathing down his neck and he could concentrate in peace.
"Mask," he muttered. After cross-referencing various incarnations of hieroglyphics, he managed to gain some motley knowledge on the text carved into the gold. Certain tiles lined up to make the character for "mask," which he doubted was a coincidence. So he kept those together as well as he could.
He randomly slid the other tiles. Maybe they would come together and he'd get some inspiration.
He gasped.
"Gods!" he cried. "Mask of the gods!" He slid them in place. The box clicked steadily. "Okay… so the rest…" His eyes burned. He wanted to rub his forehead, but his mask was in the way. "Mm, dammit." He toiled a little while longer. "Mask of the gods, mask of the gods. I've never heard that term referenced in any text before. Ugh, stupid cryptic Egyptians…" With what remaining tiles, he quickly managed to put more together. "Mask of the gods… jaws… I've never seen this symbol before…" he muttered, fingered the inscriptions. He slid one a little. The box clicked, and then a hiss of pressurized air.
He hastily stepped back. "What the hell?!"
The lid clicked, ajar.
His heart fluttered in his chest.
He grabbed a long-handled tool next to him, and, from a few feet away, cautiously lifted the lid. Ugh, at that angle he couldn't see inside well enough. His brows furrowed. The inside of the lid was a gleaming gray metal, much like stainless steel or titanium.
Neither of which the ancient Egyptians had.
He stepped closer.
"Ugh. What is that?!"
A roiling black sludge. It bubbled up against the silvery confines. He poked it with his tool. Threads of black grasped onto the utensils tip. It clung, pulled. He tugged the tool back. The threads slowly sank back, dissolved into formless black.
"Holy shit, it's alive," he gasped. "The Shadow of Horus."
He turned, hurried to the phone. His boss needed to hear about this.
Behind him, a wet slap echoed against metal. He glanced over his shoulder. The black sludge roiled and crawled over the lab table. It stretched and regrouped, an amorphous, sentient blob.
He gulped, backed closer to the corner.
His heart fluttered faster. It pounded and made his vision swim. He tried to reason himself out of his fear, but it was futile. Instincts could not be ignored.
He made a dash to the airlock.
It slithered like a snake, but faster, launched at him and wrapped around his ankles. He stumbled. His fingers curled around the edge of a wheeled tray, but it fell with him. He hit the ground hard. Tools scattered all around him with metallic tinkling.
The sludge's deathly cold percolated through the suit, and he shuddered in horror. He kicked his legs desperately, but it clung to him. It groped up around his leg. His eyes grew wide.
It was looking for a way in.
He screamed and kicked his legs again. "No!"
It reached his hip, and he tore at it. It clung to his hand, shifted perfectly around his wrist. He gasped. The inside of his mask fogged up.
It investigated the seal between his gloves and his sleeve. He tried ripping at it again, but it stayed coiled about his arm. It parted the seal with amazing, terrifying dexterity. It slipped between his inner and outer gloves.
He tried tugging it out, but it slipped through his fingers like water. Cold slickness touched the bare skin of his arm. He gasped. The coldness spread through his arm, numbed it. He whimpered in horror when he realized he could no longer feel the wetness of it touching him anymore.
It was inside him.
He stumbled up. The edges of his vision fluttered black. The cold curled through him.
Before he lost consciousness, he managed to slap a hand on the red containment button.
An alarm trilled, lights flashed red. His vision faded to black.
They'd all received the page at the same time, but they came into the laboratory one-by-one. She turned up last.
The doctor squinted through the flashing red lights. Her colleagues were all gathered before the window peering into the quarantine zone. They murmured,
"He opened it."
"What happened?"
"He doesn't look too good."
"No. Why did he take his suit off?"
She squirmed her way to the glass.
Her coworker sat against the wall in his underclothes. The suit was discarded around him. The puzzle box sat opened on the lab table.
His eyes, eyes that she knew were once brown, glared a bright red. Shadows lingered on his cheeks. He looked clammy, pale, sickly.
He stared at them through the glass. He blinked slowly. His lips parted. The gathered scientists waited with baited breath.
"This host..." his voice was deeper, it seemed to vibrate the glass even as it crackled through the speaker. "... is inadequate."
END PART
The Millennium Puzzle is the box itself. SCREW THE RULES, I'M A FANFICTION AUTHOR. HA.