A/N I've received several reviews asking me to write a sequel for Harry Potter and the Chappa'ai. I haven't done so earlier because I had no plot for a sequel. But a few days ago I was chatting with my friend ghost chicken, and we came up with a plot.
Since this is a crossover I don't follow canon strictly, so any deviation from canon is most likely deliberate. The SG-1 time line isn't canonical. This story takes place in 1998 and loosely corresponds with the end of the first season of Stargate Atlantis. For HP it's the summer following the end of Harry Potter and the Deathly Hallows.
Finally: Harry Potter is JKRs yard, and everything Stargate belongs to MGM. I'm only here to play.
I hope you'll enjoy this story. I recommend reading Harry Potter and the Chappa'ai before reading this one.
Harry Potter and the Eighth Chevron
Prologue
Jack O'Neill had loaded his video recorder with Simpsons and was just about to open a long overdue beer when the phone rang. He sighed, seeing the number, and answered.
"For crying out loud, we just threw the goa'uld into a civil war, whooped Anubis out of our existence. What now?"
"Sorry sir." Harriman said. "The general asked you to come to the SGC immediately. With SG-M."
Jack sighed. Not even a day after Anubis' defeat and there was something new.
"We'll be there..." Jack sighed and returned the beer to the fridge.
Jack called Sam and asked her to gather SG-1 while he took a trip to England to gather SG-M.
***
An hour later Jack entered the briefing room at SGC followed by Harry, Ron Hermione and Gawain. In the briefing room were Teal'c, Sam and Daniel already seated. General Hammond was waiting for them, inviting them to sit down. As soon as they were seated the general looked at them with a concerned face.
"About an hour ago we had a communication from the Atlantis expedition." General Hammond declared "They reported that they're under attack from a Wraith hive ship. Shields are holding for now, but they need help."
"Atlantis?" Hermione asked, since she was aware of Plato's legend about the Lost City.
"Wraith?" Ron asked.
"Atlantis is a city where the Ancients used to live." Daniel interjected.
"And the Wraith are some nasty life sucking aliens." Jack added.
"Life sucking?" Harry asked.
"Lacking exact knowledge about their feeding it's a viable description." General Hammond told them.
"They suck you dry, and you end up looking like those mummies we ran into in Egypt, only dead, not undead and very inanimate." Jack added.
"But right now we need to come up with a plan on assisting Atlantis." general Hammond interrupted.
"Since we know wizards and witches are related to the Ancients and that their magic is linked to zero-point energy, maybe SG-M would be able to reinforce the city shields." Sam suggested.
Ron looked doubtfully at her.
"We're not good at anything sceptological." he explained.
"Technological." Hermione whispered in his ear.
"Did you say city shields?" Gawain asked.
"Yes, Atlantis is protected by a powerful shield, which also has the potential to cloak the city." Sam said.
"That sounds a lot more like Ministry controlled magic, than the kind we cast as individuals." Hermione concluded.
Gawain nodded in agreement.
"Would this ministry controlled magic work in another galaxy?" General Hammond asked.
"The magical powers of the Ministry are imbued in the Ministry building itself, and through hard training there are those who handle and monitor the Floo network, charms like the Trace, or the magic that hides public wizarding areas such as Platform 9 ¾ or Diagon Alley from Muggles. In other powerful magical places like Hogwarts School of Witchcraft and Wizardry that power lies with the current Headmaster or Headmistress."
"All right. That kind of magic is certainly what we need here." general Hammond realised "SG-M your job is to get the wizard or witch that can handle this, and provide protection until the Wraith attack is fought off."
"I think we need to return to the Ministry and bring in someone with more insight in the Ministry controlled magic." Gawain said.
"All right." general Hammond replied.
"There's one more thing." Gawain added.
"What?" Jack asked.
"This will only work if the necessary magical power is imbued and available in Atlantis." Gawain said.
"And we won't know that until we arrive?" Jack asked for clarification.
Gawain nodded.
"So there's a chance we all go to Atlantis only to find that there's little you magical people can do other than giving the Wraith one helluva fight." general Hammond concluded,
SG-M nodded.
"Good, I'd hate if that'd come as a surprise once we're there." Jack said.
"I can always offer you an AK as an option to being sucked dry by a Wraith." Gawain said politely.
"Given the choice, thank you, but I have a six pack and Simpsons waiting for me when I get back home." Jack replied "Which I intend to do."
"Enough already." general Hammond said "You have your tasks. You have a go for a rescue mission as soon as SG-M returns."
On their way back to the Ministry they all talked about who they could bring along.
"Of course Kingsley would jump at the chance, and he'd be ideal, since he's a former Auror, can handle a fight, and has access to the full power of the Ministry since he became Minister for Magic." Gawain said.
"But?" Harry asked.
"As Minister for Magic he's not allowed to risk his life by participating in planned operations involving lethal duels." Hermione said.
"Would Percy do?" Ron asked.
"Are you mental?" Harry said.
Gawain looked thoughtfully on Ron.
"Actually that's not a bad idea. He's on the Minister's staff doing... something. That means Kingsley can give him access to most of the Ministry controlled magic." Gawain reasoned.
"And since we know the Ministry dates back to Merlin, who was an Ancient, it's likely that any magic imbued in Atlantis will be available to a current official of the Ministry Merlin founded." Hermione suggested.
Gawain nodded.
"I think that's our best shot." he agreed.
Upon arrival at the Ministry they asked for an immediate meeting with Kingsley and Percy. They updated Kingsley and broke the news of their cooperation with American Muggle Military to Percy. Finally they offered their suggestion to include Percy on the team. Kingsley looked worried.
"I really wish that we had time to research this, but with the battle going on as we speak I think this is out best chance." Kingsley concluded "Percy, are you willing to join the team?"
"Well, yes. I think so." Percy said looking rather nervous.
"You'll do just fine brother." Ron said "You fought at Hogwarts. And this time you'll have us and the Muggles protecting you."
Percy seemed to relax hearing Ron's approval. He was still feeling awkward after being reunited with his family.
"All right. I'm in." Percy declared.
Kingsley nodded and performed a series of complicated wand work, muttering a long incantation. After a faint glow around Percy Kingsley tucked his wand into his robes.
"Percy, I have given you access to all Ministry controlled magic I'm capable of. Hopefully that will help you to find and access what we seek in Atlantis. Good luck to all of you."
The group of five left the Ministry, in order to apparate to their transportation site.
"So this is what you've been up to?" Percy asked "Working with Muggle Military, American Military."
"Yes Percy. We've learned new things about Merlin and about what magic really is. Given time we might be able to develop a defence against the Killing curse and a whole range of new spells." Hermione said.
"Amazing." Percy commented.
"We're about to be transported." Gawain told them.
In a flash of light they vanished from Britain, bounced through the transporter on the Prometheus and reappeared in the SGC. General Hammond awaited them.
"That was impressive." Percy agreed, realising his Dad's fascination with Muggles wasn't unfounded.
"Welcome to Colorado, USA, and Stargate Command." general Hammond greeted him "I'm general Hammond, commander of this base."
Percy looked around.
"USA? We're in USA?" he asked.
"Yes Percy, their apparation technology is very practical." Hermione explained.
Percy, still a bit overwhelmed, turned to the general.
"Percy Weasley, junior secretary on the Minister for Magic's staff." he introduced himself.
"Weasley?" general Hammond asked.
"Yes, he's my brother." Ron confirmed "And he has all the power Kingsley could give him."
"If you're ready, SG-1 is waiting for you in the gate room."
SG-M and Percy headed down the stair from the briefing room and entered the gate room. SG-1 were geared up in full battle outfit, Teal'c looking intimidating with his staff weapon and Jack confidently holding his P-90.
"Mates, meet Percy Weasley, my brother." Ron said."
"Whackiness must run in your family Ron." Jack grinned "Your brother Bill helped us in Egypt, and now Percy here will join us for this mission, and quite frankly one has to be a bit whacko to do what we do."
Teal'c raised an eyebrow.
"Indeed."
"Don't mind them." Harry told Percy "It's just part of Jack's charm."
Percy nodded, looking a bit disappointed that the Muggle Military so far seemed rather informal. He'd expected strictness, formality and organisation, traits he truly appreciated. But thinking about it, their Auror Office, the very elite fighters, were all a bit whacko too. Must be a way to handle battle stress, right? The introductions were made short and simple since they needed to be on their way.
"General" Jack said "We are ready to leave for a rescue mission to Atlantis."
"You have go colonel" general Hammond replied and turned to Sgt Harriman "Walter, dial Atlantis."
Moments later the Stargate began spinning, causing Percy to look at it with great interest.
"Just wait until it connects, that is really impressive." Sam said "But unlike gate travel within the Milky Way we need to add an eighth chevron."
Percy nodded, despite he had no idea what Sam was talking about. Hermione noted this.
"This Stargate is like a galactic Floo network." she explained "And normally we only have to toss some Floo powder into the Floo and state out destination, but if you'd like to Floo to France, you'd have to set up an international Floo connection."
"Of course." Percy said.
"The Stargate uses symbols instead of Floo powder, and normally there are seven of them, but in this case we're setting up an international call, well, intergalactic to be specific, and that means they add an eighth symbol."
"I understand."
"Chevron eight, locked" Sgt Harriman called out on the speaker and the Stargate connected.
Percy jumped backwards from the vortex forming, but calmed down when it settled.
"This is colonel Jack O'Neill calling Atlantis. We're ready to come through. What's your status?"
The radio crackled for a moment before the reply came.
"We're holding the gate room and Central tower, but there's been glitches in the shield and the Wraith has punched through. There's man to man combat all over the city." Dr Weir's voice told them.
"Dr Weir, stand by, we're coming though." Jack responded.
"You're all clear." she replied "I'll inform Sheppard and have his team meet up with you."
"Thank you. SG-1 out." Jack finished and turned to the others "I'll go first with Teal'c. SG-M follows. Sam and Daniel covers our six. I'm not taking any chances. Lock and load, wands out."
As ordered they moved out and stepped though the Stargate.
"Breathe out before you step though Percy." Ron suggested.
"Just like a Floo, right?" Percy asked with a tremble in his voice.
Ron gave his brother a friendly push though the event horizon.
"Well, not exactly like a Floo, but he'll just have to see that for himself." Ron shrugged and stepped though.
Hermione shook her head before she too entered the event horizon. With Sam and Daniel through the wormhole disconnected.
***
Lieutenant colonel John Shepperd led his team back towards the gate room. Dr Weir had notified him about reinforcements from Stargate Command.
"And it's about time they arrive." John told himself.
Teyla and Rodney were following him and it was with great relief they entered the gate room. It was, however, rather discouraging to see only nine people, even if four of them were SG-1.
"Where's the rest of the army?" John asked while they approached the newly arrived people.
"We're it John." Jack said.
"Hey, don't think I'm unappreciative here." John said "But we're facing an entire hive here, pounding us with all they've got and with thousands of Wraith just waiting to get their hands on us in the very literal sense and on this city in the more figurative sense."
"Did you pass by the kindergarten on the way here?" Rodney asked noticing the teenagers in the group.
Sam sighed and turned to Hermione with a low voice.
"Rodney McKay, brilliant guy, but don't tell him I said that, arrogant and totally unaware of your talents."
Jack looked at SG-M and then at Rodney.
"Rodney, charming as always. They're here to save your butt." Jack said.
"Ha, ha." Rodney said with a bored tone.
Jack sighed. There was no time to win the trust of the stubborn Canadian, so the alternative was to shock him. Jack turned to SG-M.
"Could either of you please demonstrate on Dr McKay here exactly why you're the ones who'll save his butt? Jack asked politely "But we need him in original and unharmed shape after the demonstration."
Sam quickly whispered something in Hermione's ear.
"All right." Hermione said and drew her wand and flicked it.
Where Rodney had been standing the moment before was a warthog. Hermione cast an Imperius on the hog and made it purr like a kitten and stroke itself against the legs of Shepperd and Teyla. Shepperd looked in shock at the hog.
"Is that Rodney?" he asked.
Hermione nodded.
"What exactly are you folks?"
Jack grinned.
"This, John, is SG-M a team of three British wizards Harry, Ron and Gawain and an equally British witch, Hermione. They're some kind of modern day Ancients living in secret. We ran into them a few weeks ago and they have already helped us defeat Anubis. We also have Percy, high Ministry official."
There was a hint of pride in Percy's eyes as he heard Jack's introduction.
"All right, anything Ancient-related is very welcome." John said and looked at the warthog by his feet "You better turn Rodney back or I might get used to this and prefer him in this form."
With a flick of Hermione's wand the warthog turned back into Rodney who glared at John.
"I heard that Shepperd." he huffed and got up.
Dr Weir decided that they needed to focus at the job at hand.
"What's the plan then?" she asked.
Gawain and Percy quickly explained the plan.
"It seems to be a sound plan, but what do we need to do?" John asked.
"Let me think about how I can explain it." Percy said "You have those Muggle confusers, right?"
The Atlantis team members looked puzzled.
"Computers." Hermione clarified "All-wizarding people often have trouble pronouncing Muggle words, and Muggles are non-magical people."
"Yes, we have computers." Rodney replied, clearly convinced that SG-M would be helpful after his temporary transfiguration into a warthog, since he didn't even seem to think less of them for getting the word wrong.
"And they're access points, from where you control this city?" Percy asked.
"Yes." Rodney confirmed.
"Well, I need to find a magical access point, where I can control the magical core we hope is imbued in the city."
"And if that works?" John asked.
"I'll do what I can to use that power to apparate all Wraiths off the city and strengthen the shield magically."
They all nodded approvingly. This seemed like the best shot they had.
"What do you need?" Dr Weir asked.
"I need someone who knows the city." Percy said "And of course some people to protect me. When I access the magical core I won't be able to do anything but working on the defence of the city."
Dr Weir looked at John.
"You and Teyla go with him. The rest of you can work in a perimeter, clearing the surrounding areas."
"I'll join Percy too. I'm a Ministry employee and in case Percy needs a second opinion about how to handle the magic in the city I'm the best suited for that." Gawain said.
Percy nodded and Dr Weir looked at Rodney.
"I want you along with Sam here to monitor any changes in the systems." she ordered.
"Harry and Daniel with me" Jack said "Teal'c, Ron and Hermione, you're the second perimeter team."
With the plan finalized the three teams moved out.
"Be prepared for anything" John advised "All power is rerouted to shields, so we can't be sure life sign detectors are working. Where do you want to go Percy?"
Percy thought about the question for a few moments.
"Some kind of power central would be a good start. In the Ministry all those things are deep within the building in the Department of Mysteries. Your gate room is like the Atrium."
"That'd mean we're going all the way down in the Central tower to the Main Power Room." John said.
"If Merlin constructed the Ministry based on this city that would be a good place to start." Percy said.
Slowly they moved down the floors without opposition.
"If we're lucky the Wraith haven't penetrated the Central tower yet." Teyla said.
"I doubt this'll work without some kind of hitch." John mumbled.
To his surprise they reached the Main Power Room safely. John reported the progress on his radio and Percy drew his wand and started to examine the room.
"If there's magic there are traces of it. I only need to find it, in order to see how I access any imbued magic." Percy said while he cast a series of examination spells in the room.
"Heads up folk. We have a Wraith here" Jack's voice reported before it was drowned in gun fire.
"Teyla, guard the door. I'll be in the corridor." John said.
Jack fired his P-90 and it took the better part of his magazine to snuff the Wraith. As he reloaded two more entered the corridor. Harry took aim, eager to see how magic worked against the Wraith.
"Stupefy" he yelled and a red beam shot out of his wand.
It hit the Wraith in the chest and it collapsed, clearly in pain, but the stunner only seemed to knock the wind out of a Wraith.
"Um Harry." Daniel said a bit worried, but he realised Harry needed to find out what spells would work.
"Confringo" Harry yelled, shooting off a beam toward the second Wraith.
Harrys blasting curse hit the Wraith in the hip and killed it immediately as the explosion ripped it apart. By now the first Wraith was on its feet again.
"Avada Kedavra" Harry hissed.
Harry didn't like using the Killing curse, but this was war and a new species. They needed to know what spells were effective and this particular Wraith would be killed anyway. The green jet hit its target and it worked flawlessly. The Wraith fell limp to the floor.
"Good work Harry." Jack said "The Wraith are resilient bastards, but your spells seems to do the trick."
"I tried to stun it. That didn't work at all. But the blasting and the killing curse were effective."
Daniel looked at the two dead bodies on the floor, and the charred remains of the third one spread across the corridor.
"Killing curse from now on, right? That blasting curse will be a mess to clean up."
"It's just that the AK is so horrible and it's Dark Magic. I prefer to use it only when necessary. Against Anubis warriors there was no other option, but against the Wraith there is." Harry explained "In Wizarding Britain you get a life sentence in Azkaban if you use the AK."
Jack urged them forward to find any other stray Wraith.
Hermione, Ron and Teal'c were on the opposite side of the Central Tower, from Jack's position. They moved more cautiously now that they knew there were Wraith inside the Central tower. Harry had reported the spells he'd fired and the result. A sudden explosion made the three take cover. It was one of the gates from a walkway to the next tower that was blown. Dozens of Wraith were advancing into the tower.
"There's no stopping all of them, just the three of us." Teal'c said.
"We need to regroup with Jack's team and defend Percy's position." Ron suggested.
"Indeed." Teal'c agreed.
Hermione made a report on the radio and both teams moved towards the Main Power Room. When they arrived Percy was still examining the room.
"How's it coming Perce?" Ron asked.
"I'm getting there." Percy replied "There's magic here, but I need to get hold of it. But I'm getting closer."
They all drew a sigh in relief. There was hope after all.
"No pressure, but there's a lot of Wraith coming this way." Jack enlightened him.
"And one error by me and the magic might backfire. Wraith would be the least of your troubles it that happens." Percy replied.
Jack looked at Hermione.
"He's right." she said.
John alerted them.
"Wraith coming this way."
John, Jack Gawain and Ron left to fight them off and met them in the end of a corridor. The fight started immediately.
"If we could shut this door we'd win some time." John said and nodded to Ron "Press that button"
Ron pressed it but nothing happened.
"That's bad." John said firing his gun.
"The panel on the other side is lit." Gawain noted. "Ron, cast a shield for me, and I'll press the button and close the door before I apparate back into this corridor."
Gawain slipped though the doorway, and Ron's shield was hit by several Wraith blasts. Gawain shut the door.
"I hope Gawain blasts the panel before he gets out of there." John said.
"Of course he will." Ron said.
A few moments passed before the closed door was attacked.
"Gawain, where are you?" Ron asked himself.
In the Main Power Room Percy made progress. He accessed the imbued magic and found an several inactive charms.
"I think one of them is an Anti-Wraith charm and there's a shield charm." Percy said.
"Can you activate them?" Harry asked.
Percy moved his wand slowly. Reading residual magic wasn't like reading a book. It was hints and notions rather than a specific instruction. In the end it came down to Percy's gut feeling about the charms he identified.
"Yes, but I can't guarantee it'll work, or won't harm us." Percy said.
"We have Wraith in the Central Tower. We don't have much choice. Do it." Harry told him.
Percy flicked his wand and activated what he thought was the Anti-Wraith charm, followed by the shield charm. Harry reported to Jack. In the corridor outside Jack reached for his radio.
"Rodney, anything at your end?" Jack asked.
There was a brief silence.
"Amazing! Shields are at full power. Sensors are restored. Hold on." Rodney reported "All Wraith life signs are gone. Sam?"
"Sir, the hive is powering up. It'll go to hyperspace in a minute. They're withdrawing."
Ron apparated to the other side of the closed door the moment he heard that the Wraith were gone. Gawain was nowhere to be seen.
"Bloody hell. Where is he?"
Ron apparated back to join his team. If front of him, Jack and John appeared Gawain's Patronus.
"I'm on the hive ship. I'm locked up, so I don't think they intend to suck me dry just yet. I still have my wand, so I'll try to get out of here." the Patronus reported before dissolving in a silvery mist.
"The bastards took him." John grunted.
The radio cracked again and Dr Weir's voice called out.
"The hive is gone into hyperspace." she said "We made it. Thank you."
Gathered in the briefing room everyone gave their report. Rodney started.
"After Percy activated the shield the ZPM began recharging. It'll be fully restored tomorrow. We'll be able to dial earth, raise the cloak or the shield at full strength for a long time."
"I'd recommend a couple of Unspeakables to be sent here to research the magic." Percy added.
"Thank you." Dr Weir said and turned to John.
"We lost Gawain. He sent a message from the hive. He was imprisoned, but still had his wand." John said "Gawain saved us by closing that door. If the Wraith would have advanced further they'd reached the Main Power Room. Sam, anything on that hive?"
"We don't know where they headed." she said sadly.
"Anything else we need to know?" Dr Weir asked.
Harry nodded.
"The Wraith weren't knocked out by a stunner, but the Killing curse worked, and the blasting curse." he said.
"And a shield charm stops their weapons." Ron added.
Dr Weir looked at each one of them as she thought about how to proceed.
"I'd appreciate help from the Unspeakables. Any means that will strengthen the defence of this city is worth pursuing." she said "As for Gawain Robards. We must assume he's still alive. We'll alert our friends around the galaxy. When we know where the hive is, we'll stage a rescue attempt. Until then I suggest SG-1 and SG-M returns to earth tomorrow after the ZPM is fully charged. When Gawain is located we'll request your assistance to bring him home."
***
Three months later...
In an uninhabited solar system in the Pegasus galaxy two hive ships appeared from hyperspace. The commander on the bigger one of the two hives smiled as he saw the other approach.
"Why are we summoned here?" the other commander's voice was heard.
"We are here to offer you a chance to join us." the commander replied "You are outmanned and outgunned."
"Are you threatening me?"
"I'm stating the facts."
For a few moments nothing happened, but then the smaller ship started to move away as it covered its retreat with a full volley from all weapons.
"Evasive action." the commander ordered "Fire the main weapon."
He waited for his last order to be executed with a some trepidation, but mostly excitement. He had had lost a battle against the humans three months earlier, but that mission hadn't been a complete waste. He looked on the screen as the main weapon fired. It was a sickly green beam that hit the enemy hive.
"Report." the commander demanded.
The Wraith at sensors looked at them totally flabbergasted.
"Sir, I'm not sure these readings are correct."
"What does your sensors say?" the commander asked.
"There's no neural activity in the enemy hive's systems. And what's more, there are no life signs at all."
The commander nodded with a smile. He may had lost the battle of Atlantis, but he thought he'd just won the Pegasus galaxy.