Disclaimer, I don't own any of Marvel or Harry Potter's work and credit should be given to their creators.
Hogwarts student were all eating their breakfast when the door to the great hall opens and the Potters, Lupin-Black, the Weasley family, Tonks, Moody, the Malfoys and a few others enter. Dumbledore, noticing them, gets up and walks towards them. While Rose and Harry frowned as they're wondering why they're doing here, they get up and walk over to them.
"Uncle Padfoot!"Rose said as she tackle him in a hug as he start to spin her around laughing making her giggles.
"Mom, dad, Padfoot, Moony. What's going?"Harry asked as he hugged is parents and uncle.
"That's what I would like to know too."Dumbledore said.
"We don't know, we got a letter telling us to get here as it was important."James replied.
A brilliant light bursts forth, blinding almost everyone in the great hall. As the light fades, a woman is seen in the middle of the room, and all the adults immediately point their wands at her.
"Well that won't be necessary."The woman said waving her hand making all of the wand disappeared. Dumbledore look shocked at the lost of the Elder Wand.
"Who are you?"Dumbledore demanded.
"I'm the one who brought you all here."The woman simply replied, which made Dumbledore even angrier at her not revealing her identity.
"Why?"Amelia asked.
"I want to show you the life of the eldest Potter and to show you all that there is a much bigger world outside of your own little world."The woman replied, the student start to talk among themselves as they will finally learn about the mysterious eldest Potter that went missing. The Potters are shocked to finally able see their eldest again and to discover what he's been up to all this time. While Harry and Rose are delighted to finally meet their big brother. For a long time, they didn't know they had one because their parents never mentioned it, and it was only when they saw his name on the family tapestry and questioned their family that they discovered the truth and what had happened.
"You know about our son?"Lily asked.
The woman nodded."He's currently a member of the Avengers."
When she says the Avengers, a new excitement appears in the Great Hall, the Muggles and a few Half-Bloods are excited, while Rose is very excited to meet her hero.
"I can't believe we are going to watch about the Avengers!"Dean exclaimed.
"Who are the Avengers?"Neville asked, confused.
"They're a famous group of superheroes!"Seamus said.
"But didn't they break up two years ago?"
The woman waved her hand and a portal appeared, everyone looking at her shocked, seeing her do wandless magic as if it were so easy. Then 6 men and 2 women fell from the portal in a pile of dogs, while one of the women in the group landed in a pose.
"Ouch!"
"Shit!"
"language!"
"Guys you are squeezing me."
The dogpile group start to stand up.
"What did you do Stark?"Ask one of the blond man.
"I didn't do anything."A man with dark hair and small beard respond.
"Holy shit I think we got kidnapped by a cult!"
The fan of the Avengers in the Great Hall look at them in awe, as they couldn't believe they were in the same room as them. The Avengers start to look around trying to found out where they are?
"Where are we?"The younger woman asked, on guard.
"And how did we even get here?"The youngest man asked.
The woman clear her throat getting the Avengers attention."It was I that brought you here."
"Why did you bring us here."The woman that could past as Lily twin sister asked.
"I've brought you here to watch movies of your life and maybe prevent a future catastrophe from happening."
"Who even are you?"
"I'm a Watcher, but enough about me, I think it's time for you to introduce yourself."
"Tony Stark."
"Steve Rogers."
"Clint Barton."
"I'm Thor Son of Odin!"
"Bruce Banner."
"Wanda Maximoff."
"Alex Romanoff." The Potter perked up at the name as it was the same as their son.
"Natasha Romanoff."
The Potters, Sirius and Remus look at Alex before turning to the Watcher, who nods confirming that he was indeed their son.
"Alex, honey?"Lily asked shakily, Alex turned to look at them with a neutral face.
"Hello, Mrs. Potter and Mr. Potter."Alex said, making them flinched back at his tone."It's been a while, hasn't it?"
"It's been a while!? It's all you have to say young man! Running away like that without even thinking about the grief you've caused your parents!"Molly exclaimed.
Alex frowned."Running away? You thought I run away?"
"Of course! Everyone know you had run away from home!"
"Did you really think I ran away when I was 5? I didn't run away, I was kidnapped!"Alex said, Wanda looks worriedly at her fiancé.
"Wait, what do you mean you were kidnapped?"Andromeda frowned.
Alex sighs, knowing he'll have to elaborate."When I was 5, James and Lily were fawning over their darling son while ignoring me, so I had enough and decided to go to the nearby library. As I walked there, I was grabbed by a woman and knocked unconscious, a few hours later I woke up in a facility."
Everyone were shocked at finding out the truth, of what really happened to him.
"Oh Alex, honey..."
"Can you stop pretending to care?"Alex said.
"Watch your tone young man! Now apologize to your mother."James said.
"Don't act like your my parent when you never did before!"Alex glared at James.
"But we're your parents Alex."Lily said.
"You're not my parents."Alex glared.
"Alex my boy you have to forgive your family."Dumbledore butted in.
"They're not my family,"Alex's eyes harden."So kindly fuck off!"
There was an awkward silence as the wizards and wizards were shocked by the way he spoke to Dumbledore, after a moment Steve decided to ask a question they'd been wondering about since they arrived here.
"Where are we, can someone at least answer that?" Steve asked, they know that is probably some kind of school with how many children are here.
"You are at Hogwart school of Witchcraft and Wizardry, I'm the headmaster of Hogwarts Albus Dumbledore." Albus replied in his kind grandfatherly voice, but Natasha narrowed her eyes as she can clearly see that he's kind grandfatherly attitude was fake.
During that time the Watcher had change the Great Hall completely to make it more comfortable for the movies marathon, with a large screen descending from the ceiling in from of everyone.
Harry and Rose decide to approached their big brother, Wanda noticing them and tap her fiancé arm, Alex looked toward her and Wanda nods her head toward them.
"Hi, you may not know us but we are your younger siblings."Harry said, nervously.
"Hi, nice to meet you and I remember you, but you were a baby the last time I saw you."Alex respond politely, he knows that they are innocent and it's only their parents that he had a problem with. Harry blushed at that.
"Big brother! I always wanted to meet you!"Rose cried out and hugged him, which surprised him. Wanda watch the scene with a soft smile, as she sadly thought of her brother...
With that everyone are taking their seat with the Avengers all sitting together, Harry decide to stay with his friend. As Alex prepares to sit down, he notices his little sister fidgeting on the spot.
"Is there something you want?"
"C-can I sit with you?"Rose asked, nervously.
"Of course."Alex said softly, Rose smiles happily as she sits next to her brother. Wanda and Natasha smile at their interaction.
With that the screen turn on-
A.N: Alex was born in 1998 and his actor is Jensen Ackles. At the age of 7, he was rescued from the red room by Natasha when she left, and soon afterwards he was adopted by her.