Hey everyone. I finally started a new story on a crossover between Supergirl and Arrow.

I would like to thank Amelia-Queen-Black because it was by reading her story "Entre deux mondes" that made me want to write a story crossover of Supergirl and Arrow. A story that is great, by the way. For those who don't know it, I invite you to read it, because even I sometimes read it again, even today. Thanks to Amelia-Queen-Black. Without this author, this story wouldn't exist.

Good reading

Note: The story takes place during season 8 of Arrow and season 5 of Supergirl.

Prologue:

Earth – 38; National city

Kara and Alex Danvers were spending an evening between sisters at Supergirl's apartment. The two shared a pizza, while telling each other their anecdotes.

Kara was worried.

"You know, Alex, I'm worried about Lena."

"What do you mean?" asked her sister, putting down her glass of wine.

"I find her a little distant, it's as if she wanted to avoid me," explained Kara.

"I thought everything was fine between you since she knew who you are," remarked the elder Danvers.

"Yeah, I thought so too, but it's looks like that she wants a little space. I don't know why."

"I don't want to criticize her, but you know that Lena can sometimes seem unpredictable. It would not be the first time that she has done something behind our backs."

"I know," replied Kara. "But it was different back then, she didn't know about Supergirl. Today, she knows everything, there should be no more secrets between us."

"I'm sorry, Kara, I don't know what to tell you," Alex sighed.

"I know, and I'm sorry, too," replied her sister. "Kelly had to get away from National City to avoid Malefic, I imagine you must be sad, I'm ashamed to complain."

"I'm not worried about Kelly," said the elder Danvers. "As long as she's safe, that's fine with me. We will end up catching Malefic and everything will be back to normal."

"Until then, what do we do?"asked Kara.

"We can count on each other, it's good to share our problems. What if I offered to drown all our worries with a good glass of wine?"

"It's a good idea, but you know that alcohol does not affect me," said Kara.

"I could always order this drink that made you drunk," replied Alex, suppressing a laugh.

Kara grimaced.

"I've the feeling that the wine is already starting to go to your head."

"It's all me," said Alex, proud of her.

She was about to pour herself another glass, when there was a knock on her door. Intrigued, the two sisters looked at the door.

"Are you waiting for someone?" Alex wondered.

"No and you?"said Kara, as surprised as her sister.

"Well no, I remind you that we are at your house."

"Who can come to my house at such an hour?"

"Do you see someone with your x-rays?"

Kara focused on the door, and could see through a young couple right outside her door. They must have been in their twenties. She didn't recognize them at all.

"I see two young people at my door, but I don't know them," Kara replied.

Then she decided to go open the door. There she discovered a tall blond girl, dressed in a small leather jacket, with a young black man. Both were anxious.

"Hello, can I help you?" asked young Danvers.

"Hi, does Kara Danvers live here?" asked the blonde girl.

"Yes, it's me and my sister Alex. Who are you?"

The young black man cried, stunned:

"Are you Kara Danvers? So that means you are Supergirl!"

Shocked, Kara leaps forward as he pronounces her name.

"Go inside right away," she hissed, gesturing for the young couple to come back.

The two guests entered the apartment, while Kara closed the door behind them. Alex watched the new arrivals with a wary look.

"Who are you two and how do you know my identity?" asked Kara.

The blonde girl stood before her.

"We need your help, Supergirl," she explained. "We're not from here. We come from Earth – 1."

Kara and Alex raised their eyebrows at the mention of Earth – 1.

"I'm Mia Smoak," added the blonde girl. "I'm Oliver Queen's daughter."

"Oliver has a daughter?" Kara exclaimed, stunned. "Well then… I didn't know."

"He gets that a lot," replied Mia with an annoyed look.

"And I'm Connor Hawke," said the young black man. "I was adopted by John Diggle."

"I think I drank a little too much wine," Alex exclaimed, stunned.

"And what are you doing on my Earth?" asked Kara again, despite her surprise at the revelations.

"Supergirl, my brother William has disappeared on your Earth, and I need your help to find him," Mia replied with a pleading look.

Chapter 1

Star City; Earth – 1

12 hours earlier…

Mia's gaze shifted from her half-brother William's face to the device he was building. It's been several days since the two of them with Connor landed in 2019 in Star City. Mia finally had the opportunity to know her father, despite her aversion to him. Although she was happy to have the chance to meet her father, she couldn't help blaming him for having abandoned her with her mother at her house. She saw that he was making an effort to have a better relationship, but that couldn't make up for the lost years.

It was also complicated for Connor. It was in a time when his father John Diggle hadn't adopted him yet, and it got worse after the revelation about his son JJ who became Deathstroke. Both did everything to get to know each other and have a good relationship.

William had been working on his device in the Green Arrow's bunker for hours. Not knowing what else to do, Mia came to see him.

"William, can I know what you're doing?"

"As you've noticed, my sister, we are stuck in the past," replied her half-brother.

"So?"

"We are disrupting the time flow because of our presence in 2019, and therefore, I'm trying to find a way to make us return home in 2040."

Mia frowned, wondering if William was really serious.

"How do you plan to do it, little genius? Are you going to build a Delorean?"

"No, with the interdimensional extrapolator from Cisco, I can try to find a frequency that would allow us to travel back in time and go home."

Mia was not very enthusiastic about going back to their time.

"Good luck, Doc!" she grumbled with a sly look.

Connor joined them, quite anxious.

"I'm not sure it would be a good idea to return in 2040," he retorted.

"Why do you say that?"asked Mia.

"Even if William manages to build a time machine – which seems rather improbable to me…"

"Thank you for your enthusiasm," said William.

"We don't know what our future will be like if we go back now," Connor continued, as if he hadn't been interrupted. "Think about that, we thwarted Grant Wilson's plans in 2019, which means we changed the future, and even my father knows that his son JJ is going to go wrong because of me. We're still working on building a good relationship, but I'm not sure he will accept me later if I leave now. Coming back in 2040, I might not be Dig's son anymore in 2040."

"He's right, William, it would be too risky to leave now," Mia agreed, nodding.

But William barely listened to them and concentrated on his device, which began to flicker.

"Maybe I have something," he cried.

Mia and Connor backed away as if they feared an explosion, and a huge breach sprang out of nowhere.

"William, I don't know what you did, but stop it right away!" cried Mia, anxious.

The young man looked up and looked shocked.

"I think it's the portal and it looks like it's unstable!" if he exclaimed.

"WILLIAM…"

The breach swept away the three young people of the future.

Mia, William and Connor landed on the ground with a crash. The extrapolator fell and crushed into a thousand pieces on the ground.

"Oh no, you kidding me!"exclaimed William, getting up.

He looked at what was left of the device, while Mia and Connor stood up.

"What happened?" cried Mia, looking around. "What'd you do, William?"

"I opened a breach that took us," replied the young man lost in thought.

"Took where?" Connor asked, looking around.

"Good question," replied William.

The three of them walked down the lane in which they had landed and arrived at a crossroads, where they could see cars driving with people around them.

"Judging by the cars around us, it's not 2040, I'm sure of that," replied Mia.

"I don't recognize any of these buildings," Connor added, looking around. "So we're not in Star City either."

"We are neither in 2040, nor in Star City," retorted Mia annoyed. "Well done, William, you really did mess up. We don't even know where we are."

William looked around when he saw a newspaper distributor. The article on the first page interested him. He hastened to take a newspaper and showed it to his sister and his friend.

"Guys, I think I know where we are," he explained, showing them the newspaper.

The newspaper showed the image of Supergirl with the title: "Supergirl saves the day at National City!".

Mia and Connor looked shocked.

"National City?"exclaimed Mia.

"Supergirl?" Connor added, as if he had been struck by lightning.

"Yes, we are on Supergirl's Earth," confirmed William who was as stunned as them.

And that's it for this first chapter. I promise that Oliver will appear later in the story. We start with Mia, Connor and William first.