If you don't think this is possible then fine but this is just for the point of him being Seto's brother, so go with the story. Flames are welcomed because I would like to improve this. I made this story fast so there has to be something I can correct somewhere.

This is a normal Fanfiction so I will start it out Normally

Hiei: Sure

Hiei leave NOW! I said I was going to start this normally.

Hiei: But I already brought Kurama and Kenshin. For some reason they didn't want to come

Fine

Hiei: (...no sweet snow) Stares wondering what to do

Kurama: Still in Hiei's hands HIEI PUT ME DOWN!

Kenshin:Turned into Battousai when still in Hiei's hands PUT US DOWN NOW!

Hiei: Looks up no

Hey Kurama can you say it

Kurama: Sure if Hiei Puts me OWWW! Dropped on the ground by Hiei. She doesn't own Yugioh or any of its character.

Big Smile Thank you

Seto laid in the hospital in a coma. Mokuba didn't know it was going to be that bad when he told him but he knew it was going to be bad. He just expected him to faint or yell not go into a coma. Yet it was somewhat of Mokuba's fault.

Flashback

It was a quiet day at the Kaiba residence. Seto had gone to work and Mokuba was left alone with nothing to do. Normally he would play his games until Seto got home but this time he decided to do something different. Calling up a hospital he decided to get some info on his family. I mean they never tried so what could go wrong. After awhile the results came back and they called Mokuba back. Once they told him he dropped the phone in horror as they spoke. They said that they had told him too and that he was coming over. Mokuba almost fainted at the news and slowly made it to the couch flipping threw the TV channels. He wasn't even watching it, he was just afraid of what Seto might do. Knowing Seto he knew he might even kill their brother.

A knock came to the door after an hour had passed and Mokuba ran to the door and opened it just enough to see his brother's face. A nervous laugh came from his mouth as he opened the door wider. His brother walked in sipped his drink in his hand. Mokuba still couldn't believe it.

It was about the time that Seto got home and he did. Once he walked into the house he froze.
"Mokuba what is HE doing here?!" You could feel the venom dripping off of his words yet his brother just smiled as Mokuba nervously laugh.
Seto just held his head in his right hand shaking it in a confused motion and walked a bit close.
"No I don't want a reason, I just Want. Him. OUT!!" Seto was past the limit of emotionless face it was all anger now.

Mokuba got up and stood at Seto feet looking down.
"Umm Seto, I know your going to be mad but he's our older brother."
Kaiba froze.
And stared.
And stared.
And stared.
And Fell to the ground.

End of Flashback
Yes it was all Mokuba's fault for he was the one who introduce Seto to his older brother. Maximillion Pegasus.

There see it was normal

Hiei: Asleep

Kurama: Asleep

Kenshin: Asleep

Gets up and kicks Kurama and Kenshin How darn you two sleep!

Kenshin: Why did you let Hiei sleep?

Kurama: Why?

Because Hiei has been Very Good

Kenshin and Kurama: Has not

Give me one reason

Kurama: You remember your ice cream cone

Yes

Kurama: Hiei ate it

No he didn't because I never told anyone I had one so you must of eaten it.

Kurama: NO I DIDN'...

DON'T YELL AT ME AND AS PUNISHMENT YOU WILL SAY THE END.

Kenshin: laughing

Glare Shut up

Kurama: Please R&R

All the fun I have messing with these three. I don't think I will ever be bored