A/N: I don't own Kingdom Hearts nor Marvel. After watching the MCU and Endgame, I decided to write what if Sora ended at the MCU instead of Vernum Rex world? Well here it is. This will take place during the first Avengers. Will I make the sequels? Probably not but you'll never know. With that said... enjoy.
Kairi couldn't believe it... One minute She and Sora was sitting together on the Paopu tree together the next minute... he vanished. Tears came flowing out of her eyes. Her other friends were shocked as well to see Sora fade away like that. Riku then turned to the King.
"Mickey, what happened?" The king sighed.
"I was afraid this would happen, Riku." He said sadly then he lowered his head. "He took Kairi's place so that she won't be stuck in the darkness."
"So he's gone?" Asked Donald. Mickey nodded his head thus answering his question.
"Where did he go, Mickey?" Asked Ven.
"He went to a far away world, Ven." Aqua explained. "Once he used the power of waking, it transported him to a far away world that he might never come back." That shocked everybody. Including Isa.
"Is there another way to get him back?" Asked Xion. The king sighed.
"I don't know..." He then raised his head back up. "But Master Yen Sid might. He told me about this a long a time ago."
"Then what are standing around here for?" They all turned around to see that Kairi is walking up to them with a hopeful smile. "Let's get my Sora back." The gang cheered as they walked to the Gummi ship fly for their next adventure.
Yen Sid's tower
They all arrived at Yen Sid's tower as they explained Sora's disappearance. Yen Sid stroked his beard as he sighed sadly.
"I see. Sora used the power of waking and replaced Kairi then he faded away."
"Do you know where he is, Master?" Asked Goofy. Yen Sid closed his eyes then he raised his hand to show a hologram of Sora unconsciously lying on a mysterious ground. Kairi closed her mouth in fear.
"As soon as he freed Kairi from the realm of darkness, Sora faded away into a far away world called Earth. Very soon he will meet a man whom is searching for heroes. Mickey gasped.
"You don't mean he'll run into..."
"Yes, Mickey." Yen Sid answered. "He will run into our old Friend Nick Fury." Riku raised an eyebrow.
"Who's Nick Fury?" Yen Sid didn't answer with a sentence. Instead he showed them a hologram of a man with dark skin, wearing a black trench coat and has an eye patch covering his right eye.
"He is the commander of an Organization called SHEILD. However unlike Organization XIII, SHEILD'S goal is to protect the worlds from those that do harm. He is recruiting a team to help him protect their worlds. He calls it the Avengers. He came to our dimension a long time ago and we helped him got home. Before that I had a vision that a Keyblade wielder or two will come to his dimension to help him foil the plans of Loki, son of Odin. Odin is the king of Asgard and one of my personal friends. I told him to watch out for a Keyblade wielder in case something terrible has happened and I believe it has."
"Wh-what happened?" Asked Ven. Yen Sid closed his eyes. then showed a hologram of a man with dark brown, green eyes. He's wearing a green trench coat and is holding a golden bladed staff.
"Loki stole a cube that contains an infinity stone. These stones contain a power that cannot be matched. He plans to use the stone to find the others. Unfortunately my magic can't show what stone he has. Only that he has one. And it's up to Sora and the Avengers to stop him. However they both need some assistance but only one of you must go to the dimension, help Sora stop Loki and bring him back home." He said as he finished explaining.
"Why one?" Asked Riku.
"Because you all have the power to travel to the world Earth but only one of us have the power to bring him back. It's not me because I don't have that kind of power." Mickey said sadly.
"Then do you know the one who is?" Asked Roxas. They were silent before Riku spoke up.
"I'll go... Sora's always counting on me to bail his butt out of there and I gotta do it again." Yen Sid shook his head.
"No, Riku. You don't have that power either. Only one power that can lead you to the world Earth and bring Sora back is the power of love." The Keyweilder's eyes widen.
"LOVE!" They all exclaimed. Mickey nodded.
"Yes... And since Sora's mother and father aren't keyblade wielders, Only the person that loves Sora the most has the power to bring Sora back." They all looked over to Kairi whom was confused at first.
"Me?" She then blushed.
"Yes, Kairi. After you and Sora shared a paopu fruit together. Your destinies became intertwined and became a part of each others lives." Mickey explained.
"But... I don't know how to use it. What if I mess up and go to another dimension? What if..." Riku puts his hand on Kairi's shoulder.
"Kairi... you can do this... Just listen your heart with your Keyblade and you will find him." Kairi looked up at her friend with at first doubt until she feels someone touched her heart from behind. She turned to see an invisible Sora giving her a smile.
"You can do it, Kairi... I believe in you." He told her before he faded away. Kairi's eyes began to water then she turned around and faced her friends.
"I'll do it! And when I see him... I'm gonna knocked that lazy bum's head off." She said with a determined look. She then turned to Master Yen Sid.
"So, what do I do?"
"Just raise your Keyblade, think of Sora and your heart will seek the world he's at." Yen Sid explained.
"You might not be at the same exact location as Sora but you will arrive at the same world as he does." Kairi looked up at Yen Sid's wall. She closes her then opens them up with a smile. She wields her Keyblade to open a gate. She turns around to look at her friends one more time.
"Well I'm off." Riku gives his smile then he walks over to hug her.
"Good luck, Kairi. May your heart be your guiding key." Kairi smiled as she releases the hug.
"I'll be right back... with Sora." She told them as she walked to the portal as her adventures awaits her.
And that's chapter one of Avenging Hearts. I hope you enjoyed the first chapter. There's plenty more where that came from. Next chapter is where Sora is. And don't worry. He and Kairi will reunite sooner than you expected. There will not only be SoKai fluff but Sora bonding with the other Avengers.