I do not own any of the source material for this story. Reviews and constructive criticism are greatly appreciated.

…

Harry Potter was not afraid of death, but he had hoped to meet a peaceful end after a long, happy life with a family of his own. Instead he'd been forced to watch as a cosmic abomination of unimaginable power swallowed his world and subjected its inhabitants to a fate far worse than death.

Dormammu.

Harry thought he'd seen true evil when his scar burned with pain and he looked into the dark hellscape that was Voldemort's mind, and while Tom Riddle had undeniably been the pinnacle of human vileness, even he paled in comparison to that… thing. Harry only knew its name because the entity had announced itself with prideful arrogance the instant it had been summoned into his dimension by a foolish dark wizard. The destruction and subsequent assimilation of his universe had not been instantaneous, but it had been very quick all the same.

Dormammu had been summoned at Stonehenge, a place steeped in magic and perfect for such rituals. The Dark Dimension had spread out rapidly from there, creating massive ripples of dark power that Harry sensed the way a crocodile detects moving prey in water. Overwhelmed and unable to muster up any thought more coherent than an absolute certainty that he was about to suffer a fate worse than death, he'd reacted on instinct and with a desperation that dwarfed anything he'd felt during the war.

He'd cast out with magic and Legilimency, sending out a call for help that rippled across dimensions. The strain of sending the message very nearly killed him and he doubted anything would answer it, but as it turned out something had been listening. The Dark Dimension was seconds away from consuming him when time slowed to a crawl.

As the world around him dissolved into darkness and sinister, multi-colored auras, a humanoid outline of crimson and gold flames appeared before him. "Hello, Harry," it said.

Harry stared. "Who are you?" he found himself asking. The ghostly fire form seemed to brighten, but Harry didn't look, squint, or blink.

"I am the one who holds the power. I am the beginning, the middle, and the end." The fiery being's voice was unlike any Harry had ever heard before. As a wizard he was no stranger to unusual voices, but this took it to another level, as though fire had somehow learned to speak. The voice crackled and billowed, the words echoing with power. As well, it was impossible to assign a gender to the voice. The pitch seemed to fluctuate ever so slightly with each syllable, creating a tenor unlike any he'd ever encountered.

"Do you have a name?" Harry asked.

The being seemed to brighten for a moment. "I have been called many things. Balance, Destruction, the Original One, the Spark that Gave Life to the Universe, the One Who Sings the Endsong. But the name I prefer, the one I go by when I walk the mortal world is… Phoenix. I sired the magical firebirds that share that name."

Harry considered that. "Why are you here?" he said after a moment.

"I have watched you for a long time, Harry Potter," the being said. "From the moment your mother gave her life to save yours you have been of interest to me. Since then you have grown in body, mind, magic, and spirit. I never interfered on your behalf, but I watched, and I considered." Before Harry could even form a response to that it spoke again. "You called for help and I have answered. What do you want, Harry Potter?"

Harry licked his lips. His throat suddenly felt very dry, and he was certain his difficulty breathing had nothing to do with how time had slowed. He glanced behind him at the small bed where little Teddy was frozen in mid sit-up, confusion and fear written on his tiny face. Harry's godson had only just turned three and was spending the night at his house. "I want," Harry said carefully, turning to look at the fiery form that stood between him and the encroaching darkness, "to save my godson. I want him to live the life he chooses, away from the horrors I've endured, safe from whatever that," he indicated the darkness, "is."

The fire being nodded. "I can give you the power to make that happen."

Harry found that he wasn't surprised by this. "What's the catch?" was all he said.

"There is no catch. You are worthy of my power. You are the perfect vessel, if you can control it. Can you control it, Harry Potter?"

"I doubt it. But I have to try."

The fire being nodded again and held out its right arm, revealing a detailed human figure sculpted from ghostly fire. "Take my hand."

Harry stared at the hand for a long moment. Then he glanced from the hand to Teddy and back again. Moody would have killed him for being so reckless, but what other choice was there? He closed his eyes. He took the offered hand.

And something vast, powerful, so unimaginably powerful, invaded his body and swept through his entire being. His mind, his very soul, were fused with a fire so bright that to call it hot was to call an ocean a puddle. It drove all rational thought from his mind with the sheer force of its presence. He reacted on instinct. The darkness swallowed everything, the fire consumed the darkness, and the world vanished.

...

In a hidden research station tucked within the depths of the Antarctic ice, not far from the south pole of another version of Earth, alarms began to ring. Sensor detected massive amounts of electromagnetic energy flowing across the entire planet. Cell phones and other wireless communication devices went berserk, and power grids worldwide flickered. The northern Aurora Borealis appeared as far south as New York City, and their Southern counterparts were visible in Sydney, Australia.

The SHIELD Helicarrier off the coast of Maine lost ten feet of altitude in as many seconds before the initial disturbance subsided, but Nick Fury still ordered the pilots to set down in deep water away from the shipping lanes. His scientists scrambled to locate the source of the energy wave, but their sensors failed to pinpoint anything more than the fact that it originated somewhere in the eastern half of the northern hemisphere. At the secret Dark Energy Research Facility in New Mexico's Sonoran Desert, the Tesseract flared, unleashing a blue surge of energy that fried everything within twenty feet and melted its container. By some miracle, no one was hurt.

...

In a darkened chamber of the Kamar-Taj compound in Kathmandu, a Celtic woman so old she'd forgotten her own name, though she did not look it, staggered away from the Eye of Agamotto, her mind overcome with visions of fire and light, screams and birdsong. By the time Karl Mordo found her she lay unconscious on the floor, the Eye beside her. She awoke three hours later in the infirmary, though it was found that nothing was actually wrong with her. Afterwards, however, Mordo could not help but notice how disturbed the Ancient One was by whatever she had seen.

The Ancient One, for her part, spent hours upon hours of the following days in the library, until at least she found what she'd seen in her visions. A detailed history of the formation of the omniverse, and the cosmic entity that safeguarded the infinite universes that compromised it. A vast, amorphous firebird. A humanoid figure stood at its heart.

...

On Asgard, Heimdall turned away from the Bifrost gateway and strode out of his observatory at a fast clip, heading straight for the Royal Palace. The Allfather had almost certainly sensed it as well, but it would still be prudent to discuss the matter in private. The Phoenix Force had returned, and it had already chosen a host. May the Norns have mercy on us, he thought.