Title: Crossroads

Summary: There's a reason for everything, even why Salazar Slytherin lied to his friends.

Fandoms: Harry Potter, and Stargate: Atlantis (with guest stints by Stargate: SG-1)

Spoilers: Harry Potter - Everything up to Order of the Phoenix. For SG-1: late Season 8. For Atlantis: everything up to and including 'The Eye' and very vague ones to 'Before I Sleep'.

Rating: 13+ - It's like Star Wars, only with swearing.

Pairings: None. Fill in the blanks and make your own.

Category: Action, Crossover (and by extension, an AU)

Disclaimer: Harry Potter and all of its appendages are copyright to J.K. Rowling and Warner Brothers. Stargate SG-1/A are copyright to MGM Studios, Gekko, and its cast and crew. References to other fandoms are absolutely intentional.

Author's Notes: The story is set just after the Atlantis episode 'The Eye' and uses a hypothetical sixth year for Harry Potter - not because I have something against Season 2 or the latest Harry Potter book, but because I would have to revise a lot of stuff to make the plot fit again to the newer parts of the fandom, which would only delay the fic even more. I'm sure there are references in here to later episodes and the later book nonetheless since I've been editing long after they came out, but they're not intentional. Please comment and criticize copiously.

I'd like to also send out huge thank-yous to my beta, teenmisfituk at livejournal, and to Imry, Andy, and Mia for cheering me on as I write this (and continue to do so at a very, very very slow rate). I hope you guys enjoy it!

Scotland, 994 A.D.

"Fulmenos venite!"

An eruption of lightning burst down from the evening sky and cascaded down towards the earth. Down below, it struck in the vicinity of an armed Jaffa convoy as they herded a group of prisoners into a clearing. At the centre of the open space, at the top of a large mound, lay their goal.

A Stargate.

In hot pursuit of the convoy, but still some distance away, were four riders on horseback, two men and two women. They rode hard, urging their horses to cross through forest and shrubbery as fast as they could safely go, only upping the speed further upon entering the clearing a moment after the Jaffa.

Up ahead, the Jaffa leader cursed angrily at the sight of the pursuit.

"Kree, Jaffa!" he shouted, taking aim at the riders with his staff weapon, "Two of you to me! The rest get those Tau'ri through the Chaapa'ai!"

Instantly, his orders were obeyed. Two of the Jaffa joined their commander at the rear and immediately began firing at the incoming riders. The others kept the prisoners clustered together while an address was dialed.

The staff blasts sent dirt and debris up into the air, causing the riders' horses to shy off. One struck close enough for a horse to rear, sending its crimson-cloaked rider sailing into the air and back onto the ground with an unceremonious thud. Spitting the dirt out of his mouth angrily, he motioned to his companions.

"Stall them! Hurry!" he yelled.

Dismounting in one smooth motion, the other man planted himself firmly on the ground and stretched out an arm towards the convoy. As he closed his eyes in focus, his forest-green cape began to flap menacingly in the wind. Seconds later, his eyes snapped open, gleaming with vengeful intent.

"Incendio!"

A blazing wall of fire rose up right in front of the stargate, but was one second too early in appearing. The green-man's intent had clearly been to block passage to the gate once it had opened; instead, the event horizon of the wormhole exploded into being after his move, swallowing the fire whole in the process. The Jaffa wasted no time in herding their unwilling passengers through the wormhole as soon as the way was clear.

"No!" Green-man bellowed, furious at the prospect of losing their quarry. One of the remaining riders made a last-ditch attempt to loose a few arrows at the Jaffa, but her purple-painted darts bounced easily off their greyed armor. The chase was over.

The riding woman dropped to the ground and turned her horse loose to graze while she approached the 'gate, running one hand along the smooth naquadah rim, amazed at its very presence. From behind, Green-man skulked over, still angry, while the Crimson-cloaked man limped towards them with the help of the final companion, a tall, woman with golden hair.

"Curse those creatures! We lost them! Did anyone see the address?" Green-man asked.

"Yes," replied the archer, running a hand through her dark hair in frustration. She kneeled in front of Red-man and examined him for injuries. "I don't recognize the sequence, but it would serve little purpose even then. Wherever those people were taken, the Goa'uld are sure to outnumber us. The Council would never agree to send a rescue force, not now that they've placed a ban on the islands. You have a nasty burn on your leg Godric, but it's nothing serious. You should be fine with some rest."

"Thank you Rowena," Godric answered with a brave grin as he rose to his feet.

"At least we now know where they installed the Stargate. We should bury it immediately," the blonde noted, trying to uplift their spirits.

"I disagree, Helga," Green-man protested sharply.

"Are you mad, Salazar? There are only four of us. We cannot go back to Avalon or Azkaban now that the ban is in place, and we alone cannot defend this gate against one System Lord, let alone all of them! How can you-"

Godric cut her off abruptly. "Let us hear him out before we pass judgment. Please, go on my friend."

Salazar nodded, looking past his companions towards the horizon.

"I do not deny that you are correct, Helga. Out people cannot even control the problem we brought with us from Atlantis. They have chosen to seal it on one island and then retreat to another in the process, leaving us high and dry since we chose to ignore the ban. We are divided and weakened."

He stopped here to let his words sink in before breaking out his proposal.

"The gate is a gift. We should use it to contact the Goa'uld and form an alliance with them."

"Now I know you've gone mad," Helga snapped.

"You do not trust my judgment?"

"No!" she crossed her arms and stood her ground. From the look on Rowena's face, she shared in Helga's misgivings, although not in her vehemency.

"Godric?" Salazar asked, raising an eyebrow.

Godric looked between him and the others before sighing and shaking his head. "I must concur with the others, Salazar. The logic behind your idea is most cunning, but my instincts tell me that we would not be able to hold sway with the snakes for very long. And once that happened, we would be at their mercy. It's too dangerous."

Salazar laughed. "I never thought that I would ever hear that coming from you," he observed wryly, "You're getting soft."

"To admit that we are few in number and to act accordingly is hardly a weakness," Godric argued, reaching forward to grasp Salazar's hand.

"Look, we need allies to deal with the Wraith in case they break free. Why not seek out the most powerful ones?" Salazar persisted. He wrenched his palm free and sneered. "There is nowhere else to look in any case!"

Helga cut in to offer an alternative. "Why do we not seek allies here? You look too closely at our own people, who have sealed themselves away, or at an enemy from the stars. But there are people here that have the potential to learn our craft and take up our cause. I have seen them."

"You want to train these primitive people?" Salazar repeated, aghast.

"Well, why not?"

"The potential is still random within them! It could take thousands of years before it starts to pass regularly through their bloodlines, save for those who have ancestors among our people! How could we be certain that their skill is great enough or that they could even consciously control it?"

Helga frowned. "Why do you keep making a distinction between them and us? They are us!"

"I realise that! I simply believe that they are still too young to risk introducing them to our ways!"

The debate was getting far too heated for anyone's taste, but it seemed unavoidable. They were at a deadlock, and Godric scrambled to come up with a compromise.

"What about the children of our people that live among them? Would you object to teaching them?"he blurted out. To his surprise, Salazar didn't even have to stop to think about it.

"Of course not! What do you take me for? I would never abandon our people!"

"I'm sorry, it was not my intention to suggest that. But if this is so, then why do we not choose and instruct those in our own ways?" Godric boldly offered. "The important part is that we do this together. There is no greater strength we can have except unity."

Helga and Rowena nodded in agreement, seeing no need to voice any specific opinions that they had until Salazar responded. He considered the proposal carefully as he stared upwards at the night sky. The clouds generated from their conjuring had long since passed, revealing the brilliance of the stars and crescent moon.

"Very well," he conceded unwillingly, "but I will never approve of mixing with our younger incarnations."

"That is your prerogative, Salazar."

"And what of the 'gate?" Salazar asked, bringing the topic of what to do with it back to the forefront.

"We will bury it here and build our school on top of it so that we never forget where it is," Godric decided.

As they retrieved their horses after adjourning the discussion, Salazar trailed behind, analysing the situation. He had not truly wanted to go along with Godric's plan. He thought it would prove to be folly in time. He also recognized that his disagreement was generating a rift between him and his best friend already, and he suspected that it would take some time to repair.

He would go along with this plan nonetheless. He could not make an alliance with the Goa'uld on his own. He was not a fool. Even so, now that he was left to his own devices, Salazar Slytherin formulated a plan to preserve and protect the Stargate in a more accessible area.

Just in case they changed their minds.

A hundred feet below Hogwarts' school of Witchcraft and Wizardry, the remains of the basilisk lay on the cold stone floor and rotted. From above, an ageing pillar, damaged by its release, finally crumbled once and for all, landing on the carcass and striking the remainder of its jaw, cracking the teeth. The acid innards came bubbling out and slid onto the stone floor, condensing together in an oozing black pool.

Over the next few years, the acid slowly would eat away at the limestone floor, eventually creating a hole.

Instead of exposing packed earth to the room, it opened to another chamber, allowing the first faint light the Stargate had seen in a thousand years to shine through.