Notes before reading: I'm starting with what I see as canon Harry (but after years of non-combat) and will slowly develop him further throughout the fic. Harry will be challenged in this story and he's going to have a rough and clumsy start, because he's in a new place and he's rusty. If you want Harry to have the easy button in fights then this is not the story for you. I'm writing this story with certain battle mechanics in mind and I do carefully think about what actions are appropriate in different situations; factors include but are not limited to: the kind of light and sound that spells make when cast (making spells detectable) and how much time each spell requires to be cast and shot off (read this as evadable).
I've interpreted the Department of Mysteries as a research facility, not some super-Auror, secret and clandestine organization. I'm trying to keep the way his world works as close to canon as I can.
It is also impossible for me to consider every variable, so if you see something you disagree with or you have a question, please bring it up. I love learning or re-evaluating something in a different light. If you do catch an error significant enough, I will try to change it, if not, acknowledge it at the end of that chapter.
I've classified this story with the sci-fi label because 1) the Marvel Cinematic Universe movies have so far been sci-fi (including Thor) and 2) math and logic is an important part of canon HP magic.

Harry Potter, Unspeakable Magical Researcher in the Department of Mysteries, picked up his robes from the coat hanger. He was out the door with one arm in a sleeve while the other arm was still trying to find the other sleeve.

Walking through the empty marble hallways, he reflected on how he got here. He had always thought he was a normal bloke just placed in extraordinary circumstances. He didn't have killer instincts, no ridiculously powerful magical core, not as intelligent as Hermione, and despite the first half of his life, he emerged reasonably ... balanced. He was under no illusion about his success over Voldemort; he wasn't a hardened veteran but an extremely lucky boy with talented wizards and witches behind him. After the battle at Hogwarts, Harry could finally breathe; he had traveled a little afterwards to see the places he had been to before (but without the running-for-your-life part).

He didn't look his age, but at forty–one, he had grown into a solitary life with thank goodness, no action. No Ginny. No family, but plenty of supportive friends. He wasn't comfortable enough with anyone to share his problems and that included Ginny.

It had been a difficult choice at first, but after several years of their Hogwart's graduation, Harry had noticed that he had not aged and finally convinced himself that he had made the right choice not to involve Ginny. He still looked like a teenager and while that was alright for the first couple of years, he was forced to use glamours to age his face later on. A little make-up helped in situations where using magic was not allowed.

His lasting youth was a continuing puzzle for him and the main reason he had declined an offer of a more action-filled life as an Auror to a quieter career path in the Department of Mysteries. If you were going to solve a magical mystery, the DoM seemed like the smart option.

The DoM wasn't as exciting as the recruiters made him believe, but maybe that was because he was used to a different kind of excitement. It turned out to be something like a semi-retirement, compared to the troubles from his teenage years. While not as studious as Hermione, he had managed to apprentice himself to an Unspeakable. At first he was given inventory duties and confiscated dark artifacts to classify.

It was rather boring, but a safe start for any apprentice.

To do anything past that, he had to earn trust. It was the hardest thing he had to work for; he had thought Moody was exceptionally paranoid, but the Unspeakables were of the same stock. The difference was what the paranoia was applied to; here it was for small details, attention to equipment, the safety of its members and the continuation of their considerably hazardous work. Working with dangerous artifacts tend to do that to people.

Harry stood in front of a door. He was finally here, finally able to request this specific assignment. He took a deep breath before entering the Death Room.

The chill and small breeze always unnerved him. The draft did not come from outside he knew, but from what he assumed was the Veil. Its tattered and ghostly drapes ever swaying to some beat he had no way of hearing. He circled the gate like he had before over the course of a couple of months.

Every Unspeakable was assigned to the Death Room at least once. This was his turn. He didn't think he could come up with anything new from his time here, but he was more than willing. After almost two decades, he believed what was giving him his prolonged youth had something to do with the Deathly Hallows. He thought snapping the Elder Wand, throwing away the Resurrection Stone, and hiding away his Invisibility Cloak would be the end of the legend – the end of the death and betrayal that always accompanied those magical objects.

Now though, he wasn't sure. The Resurrection Stone always came back to him. He would drop it in some hole, but a week later, someone would find it and try to pawn it off. It would end up back in Harry's hands when Aurors would raid the shops for dark artifacts. The stone would give off a hint of dark magic, enough to end up in the Department of Mysteries to handle and store. There were a dozen case numbers for the same stone. It would gain another one when Harry thought up of a more clever way of getting rid of it, but eventually Harry gave up. He would keep it; better with him than someone else.

Harry shivered. It always felt like someone was with him in the Death Room, someone standing behind the gray rippling veil, watching him, always silent. He wondered if his godfather was watching. Harry had moved past the sharp grief long ago, but there was still that lingering ache in his breast. His life might have played out differently if Sirius was still alive. Harry shook himself as he pulled out a quill and a roll of paper from the inside of his robes. He did not want to think about "what if."

From the corner of his eye, he saw the frail cloth quiver – a little faster than normal.

"This is new." Harry stepped up onto the dais and placed a hand on the doorway. "Padfoot, if that's you, stop playing with the curtains," he joked. Behind him, the quill was hard at work, scribbling furiously on the floating parchment, recording his words.

The cloth rippled in an odd way. Harry thought it looked like someone's finger was tracing lines up and down the veil. He took a closer look, mindful of the dangerous position he was in. He didn't think Sirius would appreciate him falling into the veil accidentally.

As he leaned a little closer, he put more weight on the hand he had on the gate. He didn't see the minute cracks that were crawling on the ancient stone; he was too engrossed in the patterns on the veil. Patterns he didn't recognize.

The stone finally gave way and crumbled under his fingers. He tried to pull back but his balance was already tipped forward.

"Bloody Hel – " were the last words he spoke before his fingers dipped into the cool veil.

Harry stirred and blinked. He hadn't felt such a headache since the colossal hangover he had gotten the morning after Ron's bachelor party fifteen years ago. Where was he now?

His eyes focused and then strained. It was all white; there was nothing to focus on. He held his head in his hands as he rolled over to his knees. At least he still had his glasses – miraculously unbroken and still on his face. He shook his head to clear the pain, but the shaking made it worse. He groaned out loud.

"Harry Potter."

Harry whipped around, hand on his wand holster. He saw no one.

"I have a riddle for you."

His eyes searched all around, but the voice was everywhere – echoing.

"There are two sisters…"

"I don't care. Who are you?"

"… one gives birth to the other and she, in turn, gives birth to the first."

"Where are you so I can kick your arse? If this is some bloody joke…" This better not be a prank from one of the guys back in Department.

"Who are the two sisters?"

Harry noticed a far off light in the distance. It was hard to distinguish from the rest of the white but he pushed through the pain in his head and started walking in the light's direction. In the back of his mind, he questioned the wisdom behind it. Weren't there sayings that tell you not to walk into the light?

The closer to the light he got, the thicker the air became. It was like a foggy morning, he thought, except much creepier.

He couldn't see much past his nose, so it was no surprise he stumbled on something. It was soft and warm. He scrambled back and pulled out his Holly wand.

"Do not speak unless you have the answer," the creature warned.

Harry snapped his mouth shut. He followed the gigantic paw – it was easily as big as he was tall – to the creature's body and finally its head.

Harry was about to say "You're a sphinx" but stopped in time. She would take whatever came from his lips as his answer. He could only guess what the consequence was if he answered wrong. What was a sphinx doing here? A gigantic one too. Where was here anyway?

Well wherever he was, he didn't see anything else. He watched the Sphinx as she waited. Harry should have paid attention to the riddle before blabbing. What was it again? Something about two sisters giving birth to each other? Sounded sick, he immediately thought.

Alright, alright, get back on track Harry. Sounds like a cycle, one leading to the other. With two phases.

"Day and night?" Harry blurted. He backed up just in case he was wrong. He could always try to run.

A second passed, then two, then three. Harry sweated. Did he answer wrong?

"Correct, Harry Potter."

He sighed in relief.

The sphinx lowered her head to get a better look at him. She had thin fur framing the edges of her face, wavy brown hair covering her head and shoulders, and large black eyes watching him calmly. She's beautiful, he distractedly thought.

"So what am I doing here? And who are you?"

"You may pass. I am the Gatekeeper."

"What gate? And how did I get here?"

"The one behind me. You are here because you passed through a Gate."

Harry tried to peek around her huge form but he saw only more white. "Gate? You mean the Veil?" As soon as he said it, Harry finally realized that he had in fact passed through the veil. This wasn't how he imagined his own death. He was shocked, he was angry and dammit, he was embarrassed! He could just imagine the spectacular obituary now: Wizarding Savior Off-ed Himself by Veil. "I just passed through the veil…" he groaned out in shame.

Then he remembered something. "Does this mean Sirius is here? Did he have to get through you too?"

"Sirius Black did not pass through here. You are special and thus here."

That special part didn't sound too good.

"Great…Dumbledore was wrong. It's not the next great adventure but a pain in the arse," Harry muttered privately. Looking back up, he asked, "So what am I doing here?"

"You are here to pass through the Gate behind me." Harry didn't appreciate the repeat answer. He didn't think he'd get an elaboration so didn't bother asking. Next question then. "Am I going to get back home?"

"Home is relative. To answer your question though, I do not know."

Harry thought that was a wise answer. I don't know had been the unintentional mantra of his life.

Still feeling distrustful of her, he went in a wide circle around her before going straight.

Why was he doing what she told him to do? Because he's a bored idiot with nothing to do except falling into Veils, he berated himself. Besides, he reasoned, answers don't come from gatekeepers, they come from the ones controlling the gatekeepers ... and he would bet that they were on the other side.

As he walked on, he wondered if this place was like the train station. Before he was swallowed by the fog, he heard the sphinx give him a cryptic message.

"There is more than one answer."

Tony Stark, famous billionaire and proud owner of the Iron Man suit, checked the wiring and the supercooling units for the over-sized magnets one last time. He had expanded his basement specifically for these giant magnets that ran under his house in a large ring. He was determined to get this side project right. With JARVIS, he had studied Loki's teleportation abilities – both local and long distance. If he could pull this off, he'd have one up-ed the God of Mischief and Lies. The fantasy spurred him on.

Tony went to a nearby table and downed the last of the scotch in the glass. From experience he knew he worked best while half drunk (or threatened with death). He had to get just the right amount of alcohol to achieve it though. It didn't help his concentration, but when it came to outlandish ideas that no one had ever thought of, well this was when his psychotic muse came out.

JARVIS's voice broke through Tony's thoughts. "Sir the magnets are successfully cooled to near absolute zero."

"Alright, power it on," Tony ordered. He heard the hum and when it continued to get louder he grew more confident. So far, it hadn't broken down fifteen seconds into the run – like last time. Tony winced, that had taken a while to replace.

"Proton-proton collision successful."

"JARVIS, don't just do one. Come on."

"Sir, this may overheat the system beyond repair."

"JARVIS, what did I say?"

"Yes sir," came the tired reply. "What was I thinking using such modest settings?"

Tony's mansion began to shake. He wondered if his house was earthquake-proof. Probably not, and even if it was, it was sitting on top of a cliff.

JARVIS's voice signaled the final lurch. "Sir, we were successful in creating a short-lived wormhole. However, there is now an obstruction in the ring structure."

Tony opened the latch to the ring chamber thinking something had come loose. He did not expect to find a teenaged boy dressed in conservative tie, sweater vest, and a black cloak lying at the bottom.

Tony stared on in shock before he crowed in delight. "I think I did it. Teleportation at least! Victory!" Tony obviously didn't think about the ramifications of kidnapping a person until about half a minute into his victory dance.

"Hey kid. Get up now." When the black haired boy didn't move, Tony became worried. The closer he got, the more concerned he became. He couldn't see the tell-tale sign of life: breathing. Tony's arc reactor in his chest gave off enough light in the chamber, but it wasn't bright enough for him to tell if the boy's color looked healthy. Everything looked like it had a blue tint. When he felt around for a pulse, he was alarmed at the coolness of the skin. He hurried and pressed two fingers to the boy's neck – he felt nothing. Now he was panicking.

"Dummy, get the defibrillator!" Tony shouted out to his robot. He didn't know what the hell he was doing. Should he do CPR? He didn't know a thing about it except what he saw on tv. Okay, okay, what did they do? He placed both hands on top of the boy's chest and pressed down several times. Then what? Tony tipped the head up and pried the jaw open. When Dummy finally rolled near the latch, Tony gave up and climbed back up to get the defibrillator. He spared a thought to Pepper and how he needed her.

He looked confusedly at the paddles in his hands. JARVIS saved him from going further into panic. "Sir, one goes to his upper right torso above the heart and the other to the left below the heart."

Tony took a deep breath, but before he could begin, the boy moved. Tony dropped the paddles and stared at the face. Nothing happened – maybe he had imagined it? Oh god, he was becoming delusional! He had killed someone by bringing him here. It was well past five minutes; the small window of time to prevent brain damage from lack of air.

Tony felt something heavy in his heart. He stared at the young face wishing that the boy would just get up and be fine.

Tony got his wish.

Green eyes snapped open to look in his direction.

AN: This will be a multi-chapter fic and the sequel to Cognosco, my other story.

BTW, this is not what you do if someone flat-lines. Tony really does not know what he's doing.