Disclaimer: I don't own Arrow or Harry Potter.

A/N: For a long time, I've more or less ended up cultivating a reputation of someone who starts stories, rarely finishes them, and often deletes them. I'm trying to get out of that habit and in the spirit of that, I'm restoring one of the few completed works I had which I was able to recover thanks to the Internet. Sadly, the old addage that nothing completely dies thanks to the Internet isn't quite true because I've tried to find ways to retrieve other works I had completed with no luck.

This story is completely finished and will have a daily upload. Please note that while this story was finished, I wasn't completely satisfied with it.

This story was originally posted as an answer to DZ2's "Queen's Syndrome" challenge and I see no reason to change that.

Harry Potter and the Shadow of the Demon

By

ArlyssTolero

Chapter 1:

The Ritual

"My lord, the process is nearly complete," an assassin stood near the robed figure said, watching his master carefully as the man who was known to the wizarding world as Harry Potter and to the mundane world as Ra's al Ghul observed the silent grounds of what had once been the campus of Hogwarts School of Witchcraft and Wizardry. Hogwarts, and indeed wizarding Britain, no longer existed aside from those who had joined Ra's' service after his takeover. Diagon Alley stood silent, the Goblins of Gringotts having transferred to other branches, the Ministry of Magic deep underground was a mass grave of all those who had been in the Ministry when Ra's had ascended through the proper method. Unlike Al Sah-Him, or Oliver Queen/Green Arrow, he wasn't going to waste his time on saving the decadent society the British wizarding world had become.

"Good," Ra's said smoothly. "Ensure our sentries keep a watchful eye. While the Justice League will head for Nanda Parbat first, they may discover us before the process is finished and the ritual begun. If that happens, all effort must be made to stop them."

"It will be as you command, my lord," the assassin replied with a bow and departed. Ra's continued to observe the grounds of the place he had once called his home and remembered when he had made the choice to destroy the decadent society of his ancestors.

After the Final Battle of the Blood War, as people had come to call it, Harry had watched as the society slowly slipped back into the same old things. He had expected Hermione Granger, at least, to take offense at what was being done. But when he really thought about it, it made sense she was fine with what happened. She had Obliviated her own family, after all, and even if she had said it was because she wanted to keep them safe and not have them worry about her being in the Blood War, Harry had noticed that Hermione had not spoken often of her parents since around their third year.

The new laws being passed, the ones Harry had been sure Hermione would take offense to, included using the Ministry's record of magical births (kept in the Department of Mysteries) to track down Muggle-born witches and wizards as newborns and replace them with Squibs born to pureblood families where possible, and Obliviate the memories of those who they couldn't replace. This would get rid of the Muggle-like filth (Squibs) and with blood adoptions in play, the Muggleborns would become wizards and witches of noble birth. It was a compromise between the Light and the Dark in order avoid further war.

Harry had argued several times with both Ron and Hermione about this, but they had refused to budge on their belief the Ministry knew what was best since it was Kingsley Shacklebolt as Minister of Magic with most of the negative influences (like Lucius Malfoy) now incarcerated in Azkaban. Harry had still stood as best man at Ron and Hermione's wedding, but shortly after he had found his tolerance for the wizarding world at its breaking point. His best friends, the people who had stood by him as he fought against bigotry, had not only supported the Ministry endeavor to switch out Squibs and Muggleborns, but taken part in it, blood-adopting a Muggle-born newborn.

After hearing of that, Harry had recast the Fidelius Charm on Grimmauld Place, locked up his vaults within Gringotts, and left Wizarding Britain, intent on hunting down Antonin Dolohov, who had managed to escape British authorities. His reasoning? Bellatrix was already dead, but one of those who had left his godson an orphan was still out there, and no one in the British Ministry seemed all that interested in tracking down the remaining Death Eaters who had managed to flee Britain.

Harry had cut a bloody swath through Europe, taking down every single Dark wizard who had aided Dolohov, interrogating them and then leaving their gutted remains in the dark quarters of wizarding commercial districts. He had finally caught up to Dolohov in the court of Ra's al Ghul, where the man was attempting to curry the favor of the Demon. Ra's, however, had seen something in Harry even then, and allowed him to deal out justice against Dolohov. Then Ra's had taken him on a tour of Nanda Parbat with his young daughter, Nyssa, alongside, had spoken of how the League knew of the world of magic, had monitored the situation in Britain. Ra's had told Harry that like Harry, he had killed his first man at the age of eleven, how he had replaced evil with death, and suggested that perhaps Harry's path had always meant to lead to Nanda Parbat.

If he had said that to the Harry that hadn't been through the Blood War, Harry might have balked at what Ra's was suggesting, but the man who had watched the wizarding world decide to separate families and steal children for their own purposes felt a sense of kinship with a man seen by many of the mundane world who were 'in the know' to be evil, and sworn his allegiance to the League of Assassins, taking up the name of Al-Anqua, or the Phoenix due to his death and resurrection.

Al Anqua had trained under Ra's and Al-Owal, and when he combined his weaponry and martial arts with his magic, he had proven a formidable force, one strong enough to finally bring in a traitor to the League: Damien Darhk. He had captured the man at Ra's' request and delivered him for judgment. Upon doing so, he had been granted the title of Horseman, Ra's' right-hand, a position he had maintained from that point (1999) until January of 2015, when Ra's had taken an interest the guardian of Starling City, Oliver Queen. Al Anqua had seen others who became so focused on prophecy, had been one himself, that he could not support the actions Ra's was taking and gone rogue, working with the Arrow and his team.

He had aided in the capture of Nyssa, trained Laurel Lance, and executed Al Sa-Her when it became clear Queen could not do so out of some misguided filial loyalty. Al Anqua had helped keep the bio-weapon Sarab had brought to the League from spreading and when Ra's had been killed and Queen held the ring, Queen had handed the ring to Al Anqua, recognizing that Nyssa would continue the feud she had with the bloodline of Al Sa-Her. Now Ra's al Ghul, the man once known as Harry Potter had no qualms about removing a threat to his power base. Far too many people, he had thought after cleaving Nyssa's head from her shoulders, would leave their enemies in plain sight, believing it better to watch them then get rid of them. The newly elevated Ra's was not one of those people.

Then had come the moment Ra's had waited for. His return to the wizarding world. He had used the Alpha-Omega on Diagon Alley, deployed his assassins into the Ministry of Magic, and personally assaulted Hogsmeade (carefully ensuring he didn't use magic at all) and as a result driving the magicals to their stronghold: Hogwarts School of Witchcraft and Wizardry. The magicals had, of course, believed they were facing Squibs and Muggles who had discovered their twenty-year action of stealing magical children from the Muggle world and replacing them with Squibs. Ra's had led his men into the Castle using the passageways that were not as well-known, those that he had discovered with the Marauder's Map all those years ago and scouted out himself to ensure they were unblocked.

*HPDC*

Two Years Ago

Ra's al Ghul crushed down the nostalgia that warred within him as he walked the halls of Hogwarts again, looking down at the Map that he held in his hand. The remaining witches and wizards were holed up in the Great Hall. Ra's had prepared for this moment during those months of exile while the previous Ra's had courted Oliver Queen, returning to Starling when he needed to. He had discovered the changes since his departure almost 20 years earlier, including the fact that the Great Hall no longer had doors. Only a Siege Shield was in place now, to keep intruders at bay. An upstart Dark wizard had attempted to attack Hogwarts some years ago. While he had ultimately failed, his attack had been on the Great Hall and the doors had crushed nearly two dozen students sitting at the Gryffindor and Ravenclaw tables. Ever since, they had depended on the Runic-based Siege Shield, designed by Hermione Granger-Weasley, to defend against attacks. Believing the attackers to be Muggles and Squibs, the magicals no doubt thought themselves safe behind the Siege Shield.

Ra's placed the map away in the mokeskin pouch he wore around his neck, the same pouch he had worn during his travels during and after the Blood War. He wondered if Hermione and Ron would recognize it after all this time. The assassins were clad in their standard armor and cowls, while Ra's himself wore that plus a stylized cape that denoted his rank. Unlike the robes Ra's normally wore, this allowed him some semblance of movement and gave him something to use to absorb incoming projectiles (or even spells, since it was made of acromantula silk). The assassins arrived in front of the large opening that led to the Great Hall, and Ra's stepped forward, examining the Runes briefly before turning his attention to the occupants of the Hall itself.

The teachers of Hogwarts along with the remnants of the Order of the Phoenix stood as a defense against the invaders should they breach the Siege Shield. In the forefront were Minerva McGonagall, Ronald Weasley, Hermione Granger-Weasley, and Neville Longbottom. "You won't pass any further," Hermione said as she eyed the man standing on the other side of her pride and joy, feeling particularly smug. "It would take an incredibly powerful wizard to even begin to break that shield, so I doubt an army of Squibs armed with archaic weaponry can do it."

"It is an ingenious design," Ra's said, watching as Hermione preened, "but you are operating under a mistaken assumption."

"What's that?" Hermione asked, still feeling a bit of smugness, though something was nagging at the back of her mind.

"I am no Squib," Ra's replied, and with a flick of his wrist, the Elder Wand was in his grasp. He launched a bolt of pure magic at the Shield, focusing his intent on piercing it, shattering that which blocked his way. The Shield held up only momentarily before detonating inward from the sheer force Ra's was bringing to bear on it. The blast knocked the defenders backward, and the League poured in, taking up positions from which they could launch arrows, throwing knives, throwing stars and cut down their adversaries. Ra's walked calmly into the Great Hall, watching as Hermione and Ron staggered to their feet. Neville helped McGonagall to her feet.

"W-who are you?" Hermione stammered. "No one could have gotten through that shield!"

"As always, my old friend," Ra's began, reaching up to remove his cowl, "you believe in what your books and numbers tell you, never embracing that magic is more than alignment, more than design, more than patterns. It is power."

The cowl fell away, revealing the face of Ra's al Ghul to the Great Hall. Hermione and Ron's expressions grew horrified, Neville looked thunderstruck, and McGonagall collapsed again. The shock of another successful assault on Hogwarts and the discovery the leader of the attack was none other than the son of two of her favored students was too much for the aging woman's heart. "Hello, Hermione. I believe the last time we spoke, you mentioned that you had chosen to steal a child from the Muggle world because, according to the Ministry, it was the right thing."

"Harry," Hermione breathed out in fear.

"I'm sorry, but Harry Potter is dead," Ra's replied coldly. "He died when he killed Antonin Dolohov. He became Al Anqua, the Phoenix, and has since ascended to Ra's al Ghul, the Demon's Head, whose presence you now stand in the presence of."

Just as the League knew of the magical world, the magical world knew of the League, and nearly every adult in the room felt as though someone had just walked on their grave. The League operated at the order of Ra's al Ghul, and if Harry Potter was Ra's al Ghul, then Ra's al Ghul despised the British Wizarding World. "W-What are you going to do?" Ron asked.

"It is the tradition of the League of Assassins that when a new Ra's ascends, he destroys his past," Ra's said simply. "Goodbye, my old friends." Ra's delivered a cutting curse to Hermione's chest, cutting off whatever outraged comment she was about to make and replacing it with a bloody sputtering, and threw a shuriken into Ron's throat. As those he once called his two best friends collapsed in their death throes, Ra's drew his blade and met the strike from Gryffindor's sword that had come from Neville Longbottom. Ra's circled his blade around Gryffindor's sharply, pulling it out of Neville's hand. The other man had only a moment to show his surprise before Ra's' blade entered his chest. Blood dribbled from Neville's mouth as the cries of the remaining magical adults were cut short by the League of Assassins.

*HPDC*

Present Day

Only the students had been left alive, and only those who swore their allegiance to Ra's on their magic were allowed to leave Hogwarts that day. Since then, aside from his brief aid to Oliver Queen and his allies against Talia al Ghul (who had seized control of H.I.V.E. after Darhk's death) and the Dominators, Ra's had been focused on a personal project. The destruction of British Wizarding Society had been necessary for Ra's to claim his spot (the rest of the League might well have rebelled otherwise) but his ascendancy to Ra's had simply been a stepping stone to fulfilling a plan he had had for years, since he had read about rituals in Nanda Parbat's archives, archives the previous Ra's had let him use so he could be an efficient assassin in the use of magic as well as their standard weapons.

Ra's sensed that the first step of the ritual, the excitation of the ley lines had been completed. Now, it was time for the second step: channeling his own magical power. For that to happen, he would need to enter the heart of Hogwarts itself, otherwise known as the Room of Requirement. Departing the Astronomy Tower, where he had been observing the grounds of Hogwarts, Ra's headed for the Seventh Floor and the Room of Requirement. From this point forward, it would be up to his assassins to keep any interlopers busy. The Room would keep anyone from entering the Heart of Hogwarts once he entered.

The Justice League did indeed try to stop Ra's, but by the time they arrived, Ra's was firmly ensconced in the Room of Requirement and even Supergirl could not seem to find a way to get to him. As Hogwarts erupted beneath them, the Justice League could only wonder, "What was Ra's' purpose in destroying the entire world using the ley lines?"

*HPDC*

August 1994

Emerald eyes snapped open as the glow that had surrounded the maltreated teenager's body faded. Rising from his horizontal position, the young man cast off his raggedy blankets and pulled his shirt up, examining himself in the mirror. His pale skin had a healthy color to it now, his green eyes sparkled with the pain of his life in the next century, and his memories swirled.

Harry Potter, formerly Ra's al Ghul, gave what could only be described as a maniacal grin as he felt the magic of the Hallows still within him. A tattoo in the form of the Hallows symbol was on his chest. Concentrating, he turned invisible without any trouble. A twitch of his hand and he briefly summoned the spirit of Rebecca Merlyn before dismissing her. He would only keep a ghost around that he required advice from, and Rebecca Merlyn was not that. Finally, he raised his hand and channeled magic into them, watching as it arced between his fingers. He was still the Master of Death and his body was honed to a deadly edge like it had been in the future.

Now he could work on his true end goal: destroying those who had laid the groundwork for what happened after the Blood War. Light and Dark alike were his targets. None of them would survive the burning wrath of The Phoenix. First things first, though:

It was time to go Diagon Alley. He had some orders to put in at various places.

A/N: Now, to answer some potential burning questions:

Aside from a few changes here or there and some editing regarding spelling and/or grammar, this story is the same as when I posted it in 2017.

I have kept mentions of the Arrowverse characters and situations purposely vague so if I decide to do an AU (a high possibility considering my strong dislike of the direction the Arrowverse as a whole has taken towards melodrama in replacement of solid story), I can do so.

As far as Harry's timeline is concerned:

May 1998 – Battle of Hogwarts

June 1999 – Harry leaves Britain in disgust

May 2000 – Harry kills Dolohov in Nanda Parbat and joins the League of Assassins

May 2015 – Harry becomes Ra's al Ghul after the previous Ra's is killed by Oliver Queen in Starling City

Sometime in 2020 – Ra's performs the ritual to send his consciousness back in time to 1994