TO SAY THE MISSION had been a walk in the park for Tony would've been a lie. Tony Stark was many things — genius, billionaire, former playboy — but well-rested was not one of them.

By the time he stumbled through the front doors of the Avengers compound that late afternoon, the sun had already begun to dip beneath the horizon, casting warm gold across the marble floors. It should've felt like home. Instead, it felt like walking into a painting that had long since faded.

"I'm telling you," Tony said, his voice tight with frustration, "there was someone down there."

He stood in the living room, the Cosmic Cube already delivered to S.H.I.E.L.D., exhaustion hanging off him like a too-heavy suit of armor. His hands moved animatedly, like he was still underwater, still reaching. "Scratch that. Not something. Someone."

Across from him, Steve leaned against the kitchen counter, arms crossed. Natasha sat on the edge of the couch, silent but alert, watching Tony like she was trying to see the truth between his words.

"There was this wreck," Tony went on, pacing now, "and inside, just as I'm about to grab the cube—boom. It was there. Barely a blur. But it saw me, and I know it saw me. And no, it was definitely not a dolphin. We locked eyes, just for a second. Then it was gone."

"Tony," Natasha said softly, "you haven't slept properly in days."

Tony stopped pacing. "That's not the point."

"It kind of is," Steve interjected gently. "You've been running on fumes since Sokovia. We all have."

"I know what I saw," Tony snapped, but the fire in his voice quickly dimmed. He ran a hand through his messy hair. "And it wasn't a hallucination. FRIDAY picked it up. Briefly. She said it was human. Human, Steve."

"Maybe it was in fact a dolphin or a shark," Natasha offered, though she didn't sound convinced.

"No fish moves like that."

"dolphins are mammals," Natasha corrected him.

"That's not the point, smarty pants," Tony said annoyed, while Steve could only roll his eyes at their bickering. "It was fast. Faster than anything I've ever seen." His voice dropped lower. "And the way it looked at me... It wasn't random. It felt like..." He trailed off, suddenly unsure. Like saying it out loud would make it sound ridiculous.

"Like what?" Steve asked.

Tony's shoulders slumped. "Like it was sad. And scared. And real."

Silence stretched between them.

Natasha stood and walked over to him, her voice softer this time. "Tony. I'm not saying you're wrong. But you're tired. You've been through more than any of us can understand. Maybe this is your brain trying to tell you to get some rest. Please. Ugh, I can't believe Fury sent you straight to next mission after what happened in Sokovia. I swear I'm gonna–"

"What did Fury say?" Steve asked serious, raising one of his eyebrows.

"He said, he doesn't believe in my mermaid theory." Tony sighed bitterly, avoiding their eyes, hands on his hips. "

"No one does", Natasha snorted with a short laugh, amused because of her best friend's conspiracy theory. As a man of science, did he really believe in mermaids?! That's just crazy, She thought.

"He said if I say one more word about mermaids, he'll put me on medical leave." Tony added.

That earned another chuckle from Natasha. "You are talking about mermaids."

Tony raised a brow. "And yet you once took down an alien army with a stick and some tiny guns. Why is this the thing that's too far? I mean, even FRIDAY said, she found something human on the radar." Tony protested yet again, but no one wanted to answer something at this point.

Steve let out a tired breath. He was so done with their constant arguing.

Still, neither of them could quite say what Tony wanted to hear — that they believed him.

With a heavy sigh, Tony gave up. "Alright. Well thanks for the lovely support, you guys." He turned toward the hallway. "You've won. I'm going to bed before one of you tries to get me a therapist again."

Natasha called after him, "Only if you start talking to fish."

"You're hilarious, Romanoff," Tony quipped, disappearing around the corner.

And when he was gone, silence fell again.

Steve stood still for a moment, arms folded across his chest, brow furrowed in thought. He turned to Natasha. "You think he's on to something?", he asked quietly, eyes lingering on the hallway.

Natasha exhaled sharply, pinching the bridge of her nose. "Steve, not you too. Don't you dare start with this nonsense as well."

"What if Tony's right? Stranger things have happened", Steve said. Something inside of him wanted to believe Tony somehow.

„You don't think that, HYDRA has something–"

"Think about it," he pressed. "The Winter Soldier. The Twins. Do you truly believe, they were the only HYDRA experiments?"

"Mmmh ... what are you suggesting?", the redhead asked, giving in a little. She may not believe in mermaids, but maybe there really was something more to what Steve had said.

"We should search for more HYDRA outposts and bases. We've let them slip through the cracks before. We can't afford to keep assuming they're done. If they're still out there... doing this to people...", he suggested, not wanting to think about what HYDRA was currently scheming at this moment.

For a moment, neither of them spoke. But Steve couldn't remain quiet. "I think," he began, "that there's more we don't know. And Tony might've seen it before anyone else."

✧˚ · .

Even after Natasha had left the room, Steve couldn't shake the feeling. It pressed on his chest like a weight — like the hush before a storm. There was something in Tony's eyes when he spoke of that thing. Something real. Something raw.

And Steve had learned long ago to trust the gut feeling that wouldn't let him breathe easy.

He needed answers. Which is why, instead of sleeping, he found himself heading down the corridor to the one person who might understand the weight pressing on his ribs like an anchor.

Bucky.

The Avengers had taken him in after the incident in Washington, after the fall of S.H.I.E.L.D. and the burning of too many secrets. They'd done it secretly, away from the headlines and the watchful eyes of government agencies. For the world, the Winter Soldier was still a fugitive. But here, inside the tower, he was just Bucky again. Or trying to be.

Steve knocked softly on the door. He waited, heart tugging with a familiar ache. Not just for the friend he'd once known—but for the man who was still fighting to remember who that friend had been.

The door creaked open. Bucky stood there, hair damp from a shower, eyes dark and guarded beneath heavy lashes. "It's late," he said, but he didn't sound annoyed. Just tired.

"We need to talk," Steve said gently.

Bucky stepped aside. He didn't ask questions. He never did—not with Steve.

Steve sat down, elbows on his knees, gaze flickering to the small stack of old books by Bucky's bedside. One of them had a bookmark in it. Another was dog-eared and worn at the spine. The lord of the rings. He smiled faintly at the sight.

"We think HYDRA's not done yet," Steve began. "Natasha and I... We think there might still be bases hidden out there. Labs. Projects. People."

Bucky leaned against the wall, metal arm crossed tightly over his chest. His expression didn't change, but his eyes clouded.

"More experiments?" he asked quietly.

"Yeah."

There was a long pause. The kind that felt like standing on a cliff's edge, waiting to fall.

"They... erased a lot of things," Bucky said at last. "Spliced up my memories, scattered them like glass. Most nights, I don't even know what's real and what's been carved into me."

"I know," Steve said softly. And he did.

Bucky looked away, jaw clenched, as if chewing on something that didn't want to be spoken.

"Stark said, he'd seen a mermaid", Steve explained. „Do you remember anything?"

Bucky didn't answer. He stared at the far wall. "I'm sorry...", he began, but something flickered behind his eyes. A tiny spark. A whisper in the back of his mind.

"You're a good man James."

The words echoed from nowhere and everywhere. Not Steve's voice. A woman's voice, soft and bright like light cutting through seawater – an angel.

"Sir—Mar—" Bucky whispered. His mouth formed the shape of a name that seemed to catch on his tongue like sea foam. "Siren..."

Steve blinked. "What did you say?"

Bucky flinched, as if waking from a dream he wasn't ready to leave. "I... I didn't mean to say anything," he muttered. "I don't even know what I said. I'll let you know if I remember anything," he finally said, voice hoarse. But Steve could see it—something was tugging at the edges of his mind, like a song half-remembered, too delicate to touch without it vanishing.

Steve nodded and stood. "That's more than enough. Thanks, Buck."

He meant it. He knew what it cost Bucky to offer even that much. Talking about HYDRA, about the past, was like walking barefoot through broken glass. But just as Steve reached the door, Bucky's voice stopped him.

"Steve," he said, and the sound was different now—soft, hesitant, but laced with something fragile and aching. "I think... I think there was a girl. Not just a memory. She meant something. To me."

Steve turned back. He didn't speak right away. Just looked at him—really looked—and saw the lines around his friend's eyes, the ghosts that still curled like smoke around his shoulders.

"I'll look into it," Steve promised.

Bucky's nod was barely perceptible. But it was enough.

And as Steve left the room, something settled in his chest—not peace, exactly. But purpose. A name. A whisper. A thread to follow.

"I believe you, Buck," he said softly to him, before disappearing into the dim hallway.

But as the door clicked softly shut behind him, the quiet felt less like calm and more like a warning.

Because somewhere, far away from the safety of their walls, a new danger was rising. And whatever HYDRA was planning—whatever this new threat was—it was moving fast.

Steve lay awake long into the night, the echo of Bucky's whispered words—Siren—lingering like a fragile song in his mind. He heard him.

Sleep was a distant dream.

And the fight was just beginning.