The sky over New York was as bustling as ever, with skyscrapers standing in dense rows and traffic flowing endlessly.
However, in the sunless, dark corners beneath the city, a secret storm was quietly brewing.
Eren slowly awoke from the darkness, his head throbbing, as countless memories that weren't his flooded his mind.
He was originally an ordinary Marvel Universe fan, but for some unknown reason, he had been reborn as a S.H.I.E.L.D. Level 7 Agent, burdened with the mission of being a double Agent infiltrating HYDRA.
"What exactly is going on..." Eren rubbed his temples, muttering to himself.
He had to adapt to this new identity and environment as quickly as possible; a slight misstep could lead to eternal damnation.
At this moment, he was in a secret HYDRA laboratory.
The surroundings were filled with various bizarre experimental equipment, and flickering lights cast eerie shadows on the walls.
Not far away, the Winter Soldier project was in full swing, with the modified soldiers, like soulless killing machines, struggling and writhing on the experimental tables.
"Hmph, this inhumane project must be stopped." A determined glint flashed in Eren's eyes.
Just then, an accident occurred.
HYDRA researchers, during a forbidden experiment, accidentally awakened the Moyun Vine that had been dormant deep within the laboratory.
The Moyun Vine, this mysterious plant from the 'Swallowed Star' Universe, possessed astonishing power.
As soon as it awoke, it rampaged wildly like an unbridled horse.
Vines stretched everywhere, crushing experimental equipment in their path, and researchers screamed continuously.
Eren's heart filled with joy; this might be an excellent opportunity.
He quickly approached the Moyun Vine, and relying on his understanding of 'Swallowed Star', he attempted to establish a connection with it.
The Moyun Vine seemed to sense Eren's goodwill, and its frantic actions somewhat eased.
Under Eren's guidance, the Moyun Vine charged directly towards the core area of the Winter Soldier project.
The modified soldiers were utterly helpless against the Moyun Vine's powerful strength.
In just a moment, the Winter Soldier project was completely destroyed, and the laboratory fell into chaos.
"Quick, seize him! He's an internal spy!" a Hydra Officer roared.
Immediately, a group of heavily armed Hydra soldiers surrounded Eren.
Eren's lips curved slightly upward as he activated the Symbiote battle suit formed by the Moyun Vine.
The black battle suit instantly enveloped his entire body, and he moved like a ghost through the hail of bullets, easily dodging the enemies' attacks.
Meanwhile, at S.H.I.E.L.D. headquarters, Director Nick Fury's brows were tightly furrowed as he closely monitored the movements in the HYDRA laboratory.
"What exactly is this Eren up to..."
Eren maneuvered around the Hydra soldiers while contemplating his next move.
He knew he couldn't stay here much longer.
Suddenly, he discovered the laboratory's ventilation duct, and with a flash, he slipped inside.
After emerging from the ventilation duct, Eren arrived at another HYDRA research area.
Here, he met Susan Storm.
Susan was a brilliant scientist, and at that moment, she was intently studying the Tesseract's energy.
"Susan, we must cooperate," Eren said directly.
Susan looked at him warily, "Who are you? Why do you want to cooperate with me?"
Eren briefly told Susan his identity and about the resonance he discovered between the Tesseract's energy and the "Yunmo Star Legacy."
A hint of surprise and curiosity flashed in Susan's eyes, "Are you serious? If what you say is true, then this will be a major discovery."
The two immediately hit it off and began to jointly research the Tesseract's energy.
During the research process, Eren keenly noticed that the Space Stone within the Tesseract seemed to have an intricate connection with the "Yunmo Star Legacy."
Whenever he used the secret techniques from 'Swallowed Star' to approach the Tesseract, the Space Stone would emit a faint resonance.
Meanwhile, at Stark Industries, Obadiah was plotting a conspiracy.
He attempted to steal Tony Stark's Iron Man technology to create his own War Machine—Iron Riot.
Upon learning of this, Eren decided to intervene.
He piloted a flying vehicle stolen from a secret HYDRA Base and rushed to Stark Industries.
When he arrived, Iron Riot had already been activated.
The massive metallic body rampaged through the Stark Industries building, leaving destruction in its wake.
Tony Stark, at this moment, was wearing his initial armor and struggling to fight against Iron Riot.
"He can't be allowed to succeed!" Eren unhesitatingly joined the battle.
He controlled the Moyun Vine, which, like black giant pythons, coiled around Iron Riot's legs.
Seeing this, Tony Stark seized the opportunity to attack, firing lasers at Iron Riot.
Under their combined assault, Iron Riot gradually couldn't hold on.
Finally, it crashed to the ground.
Obadiah's conspiracy was declared a failure.
Tony Stark was very grateful for Eren's help, and in return, he gave Eren 1% of Stark Industries' shares.
"You are a trustworthy partner, and I hope we'll have more opportunities to cooperate in the future," Tony Stark said, extending his hand.
Eren shook Tony's hand and replied with a smile, "Definitely."
After this series of events, Eren knew that his adventure in this merged Universe had only just begun.
The New York sky remained bustling, but beneath this calm surface, a greater storm was quietly gathering...