Since many writers wrote fics about their theories about Yuto the Dark Duelist and his various possible relations with Yuzu, I decided to write my own version. Enjoy! ^^

Shun was looking out of the window of the building they were hiding in. He had a thoughtful expression. Yuto could guess why.

«She can't be her. You think your sister would learn Fusion Summon?»

Shun frowned. «No. Never. But...»

Yuto let out a breath. «Listen, you know we are in the past, right?» Shun nodded. «Then, it may be possible we encountered Ruri's pre-incarnation.»

Shun looked at him with a disturbed face. «You mean...» Yuto nodded. «Her soul in a past body. It's still Ruri, but not our one.» he said. «And I heard her mention a certain "Yuya", who looks like me. Possibly one of my pre-incarnations.»

Shun looked down with a concerned face. «...the fate...» Yuto put his fist on his chest. «We'll find your sister. I promise.»

Shun closed his eyes, then reopened them and stared at Yuto. «I need another promise from you.» Yuto appeared confused for a second, then returned to his neutral self. «Sure. Anything.»

«We both know about the dangers of this mission. And if I do not return with you... You must promise me that you'll take care of Ruri. I don't want her to be alone.»

This time, the purple-and-black-haired boy looked surprised. «I... I promise this too.» He frowned, again. «But before that, I'll do anything to not leave you behind.»

The black-and-green-haired boy smiled very slightly. «Thank you, my friend.»

«And now, let me repay you for the punch you gave me.»

From my DA journal:

Today I watched the episode 24 subbed, and I thought a bit.

Remember all of that Reincarnation stuff in Zexal, and the apocalyptic future of 5D's? I think this is the same thing.

In the future, users of different Summoning methods start battling at each other, until it somehow excalates into a Civil War. Among the Xyz users, there are Yuto and Ruri, who are reincarnations of Yuya and Yuzu. Someway, the LDS kidnaps Ruri and brings her in the past (our present), with Yuto and Shun following them.

Yuto and Ruri so would be the reincarnation of Fruitshipping. This would explain why they look like our protags, and why Yuto wants to protect Yuzu.

So excuse me but I think I will risk and ship YutoxRuri.