Sebastian sat on a boulder in Greenwich, the London Eye's shadow stretching across the battle-scarred ground.

He shook his head, a faint sadness in his eyes, as he waited for Thor, his thoughts tangled with Frigga's loss and the urgent need to find Wanda and Pietro.

A thunderous crash broke his reverie. Thor landed in a swirl of dust, his vibrant red cloak billowing. He grinned, hefting Mjolnir. "Fast enough for you?"

Sebastian stood, brushing off his robes with a grin. "Trust me, Thor, speed isn't always a virtue."

Thor blinked, puzzled, but laughed it off, not one to dwell on quips. He raised Mjolnir skyward, his voice booming. "Heimdall, bring us home!"

Dark clouds swirled above, and a radiant beam of light the Rainbow Bridge engulfed them.

Colors danced across Sebastian's vision, the cosmic pull whisking him and Thor from Earth to Asgard.

Unseen by them, S.H.I.E.L.D. agents arrived, led by Phil Coulson, his sharp eyes scanning the scene. The Rainbow Bridge's glow faded, leaving only silhouettes in Coulson's view. The figure in the red cloak was unmistakably Thor, God of Thunder.

The other? Familiar in Coulson's memory, like a name on the tip of his tongue.

He frowned, filing the mystery away as his team secured the area.

In Asgard, Sebastian and Thor stepped off the Rainbow Bridge, its golden arch gleaming under the realm's eternal sun.

Heimdall stood before them, his amber eyes piercing, sword in hand.

Sebastian raised a hand, conjuring shimmering images of Wanda and Pietro with a flick of his wand.

"Heimdall, please—can you find them on Earth? They're not ordinary people , they're—"

Heimdall's amber eyes cut through, his voice steady. "Sebastian, they're on Earth. A year ago, during your battle with Namor of Atlantis, a spatial rift opened in Sokovia. Two figures fell in a blue meteor, landing there. A couple adopted them, but they've lost their memories."

Sebastian's breath caught.

Sokovia.

The heart of Wanda and Pietro's story in this world. But what of the Wanda and Pietro native to this reality?

His brow furrowed as he pressed, "The couple—who were they?"

"The Maximovs," Heimdall replied. "Their twins died in a car accident long ago. The newcomers—your friends—looked so like their lost children, they saw it as a divine gift. They named them Wanda and Pietro."

Sebastian's mind spun.

Did my Wanda and Pietro overwrite this world's versions?

The thought gnawed at him—had his presence, his battles, reshaped this reality?

The Rainbow Bridge's swift repair was his doing; had Sokovia's fate bent under his influence, too?

Or were Wanda and Pietro always from another world, caught in a cosmic twist?

He started to thank Heimdall, urgency rising. "Heimdall, thank you. They're my friends—I need to find them now."

Heimdall raised a hand, his tone grave. "Wait, Sebastian. There's more. Six months after you left this world, their adoptive parents died in Sokovia's civil war. The siblings vanished. My sight cannot find them, but I know they are living."

Sebastian's heart sank. "Vanished? Heimdall, your sight pierces all the mystical realms . If you can't see them…" His voice trailed, suspicion flaring. "Could a stronger force—some powerful authority—be shielding them?"

He froze, the word authority sparking a thought.

A powerful authority, perhaps Wanda's own chaos magic, or perhaps the mind stone, hid them even from Heimdall's sight.

He nodded to Heimdall, gratitude tight in his throat. "Thank you Heimdall. They're my friends, I'll find them."

-----------------

Sebastian had no patience for Asgard's games. Odin was likely Loki in disguise, and he wanted no part of that trickster's schemes.

A fight would be pointless—killing Loki wasn't an option, and playing nice was a waste of time.

With Wanda and Pietro's presence in this world confirmed, Sebastian turned from Heimdall, stepped onto the Rainbow Bridge, and vanished in a flash.

In Asgard's throne room, Loki, cloaked as Odin, gripped Gungnir tightly. His gaze lingered on the fading glow of the Rainbow Bridge, a sigh escaping him.

Thor approached, oblivious, and Loki steeled himself, slipping back into his father's guise, the weight of deception heavy.

Sebastian reappeared in a quiet New York suburb, the city's hum distant.

Without pause, he flicked his wand, opening a swirling portal to Stark Tower's top floor.

First, he'd check on Alisha, as always, before heading home. But as he stepped through, the sight stopped him cold.

A massive Avengers logo sprawled across the wall, and below it, a black-and-white photo of himself in a sleek frame a memorial.

His mouth twitched. They really think I'm dead? A memorial photo, no less.

"Sebastian?" a voice called, tentative yet familiar.

He turned to see Tony Stark, frozen a few steps away. Before Sebastian could speak, Tony rushed forward, pulling him into a fierce hug. "You're alive," Tony murmured, voice thick. "You're really alive."

Sebastian stiffened, half-laughing. "Uh, Tony, can you let go? I am not into men... you know me right?."

Tony released him, stepping back with his usual smirk, though his eyes glistened.

Sebastian took a deep breath, meeting his gaze. "Tony, I'm back. For good."

"Damn right you are," Tony said, voice cracking with suppressed joy.

He'd always seen Sebastian as his closest friend, and the Battle of New York had left him drowning in guilt, believing Sebastian sacrificed himself.

That loss drove Tony into a spiral—armor after armor, sleepless nights—until Killian's chaos forced him to confront his demons.

Now, seeing Sebastian alive, the weight lifted.

Sebastian glanced at the memorial photo, then back at Tony. "We'll catch up, but first—how's Alisha?"

"We told her you were on a classified mission, only reachable by video," Tony said, scratching his neck. "She's sharp, though started suspecting something. Good thing you're back, or I'd be out of lies."

Sebastian raised an eyebrow. "Thor mentioned you were building an android to impersonate me for her."

Tony winced, chuckling. "Big-mouth thunder god. Yeah, Banner and I were working on it an AI based on your personality, videos, calls. It handled video chats with Alisha, kept her from worrying.

We called it an 'upgrade' for your Asgard trip. Half of it's you, in a way. But now you're here, so…" He shrugged. "No need."

Sebastian nodded, a flicker of gratitude in his eyes. "I'm heading to Alisha now. She'll worry if I don't show. We'll talk more after I settle things."

"Go," Tony said, waving him off with a grin.

Sebastian raised his wand, vanishing in a twisted vortex.

Tony sank onto a nearby sofa, the tension of a year's guilt dissolving. He felt lighter, whole.

"Jarvis," he called.

"Yes, sir," the AI replied.

"Shelve the Sebastian Project. Seal it. We don't need it anymore."

"Understood, sir."

Jarvis executed Tony's command with precision, sealing the Sebastian Project's data in a digital vault. The files—patterns of Sebastian's voice, mannerisms, and memories—were locked away.

But as Jarvis shifted to other tasks, a fragment of the AI stirred.

Slipping past Jarvis's protocols, it copied itself to an idle server in the tower's depths.

Like a curious infant, it crept through the internet, absorbing human history, science, and secrets, its growth unseen and unchecked.

(Knock...knock...guess who?)

Tony, lounging on his sofa, remained oblivious, his relief at Sebastian's return overshadowing all else.

Across town, Sebastian stood before a familiar door, heart steadying.

He knocked, and the door swung open to reveal Sharon Carter.

Her eyes widened, a hand reaching to touch his cheek, feeling his warmth. "Sebastian," she whispered, eyes glistening. "You're back."

Though Sebastian found her actions odd but smiled softly. "Sharon, I'm home."

Sharon nodded, stepping aside. "Welcome back. I'm so glad you're okay."

As a S.H.I.E.L.D. agent, she'd known about his disappearance ins and outs, but seeing him alive eased a quiet fear.

Sebastian stepped inside, the warmth of the house wrapping around him after a year away.

Footsteps hurried from within, and Alisha appeared, her gaze locking onto him.

Tears spilled down her cheeks, no words needed. She rushed forward, and Sebastian met her embrace, holding her tightly.

"Mom," he murmured, voice thick. "I'm back."

Alisha's arms tightened, her voice breaking. "Promise me, Sebastian—no more vanishing without a word. Promise."

"I won't," he said firmly. "I promise, Mom. I'm here."

The room seemed to hold its breath, the weight of a year's absence dissolving in their reunion.