People had many different theories why the two of them were together. His friends though that he broke the ice around the cold brunet with their fights and that was the reason for them to become friends and then lovers. Mokuba though that Seto liked him all along but was too afraid to show it and acted the opposite way to get rid of the blond and his feelings. Shizuka though that her brother was just too lovely to be hated and warmed everyone's hearts. And the rest of the world though that he was after Seto Kaibas money and was just his toyboy. And if he was true to himself he didn't know the reason for them being together and seeing Seto lying next to him, he wasn't sure if even the brunet knew the reason.
But not knowing the reason wasn't the worst thing in this situation. For him the worst was what the world thought of him: A toyboy. Just an other whore being after money. And that hurt. He always thought that he was an honest person who would never be misunderstood by others on account of this quality. While Battle City the press always praised him, too. He had never hold back his thoughts on his opponents and told the world what he thought of everyone. And just a few months later everyone thought that he was a faker. Just another good-for-nothing from the slums of Domino who wanted to use the power and money of his rich boyfriend to become someone.
But when he thought back to the start of their friendship, a little smile appeared on his face. On this day they fought like they always did and suddenly a though hit him and he challenged Seto that the young CEO wouldn't be able to be friends with him and that that was the reason the brunet always turned everybody down. Suddenly a really confident glare was shared with him and Seto accepted his challenge. The result was that they hung out together for a whole week as if they were real friends. They went out together to the arcade and the cinema, they ate lunch together at school and they went home together. Well, actually they didn't go to Katsuya's home because Katsuya was ashamed of it, so he always dragged Seto to the park or Burger World. The CEO never asked Katsuya why they didn't go to his home, probably the CEO knew it already and just didn't want to mention it, knowing that Katsuya was uncomfortable with this topic.
But the blond was even more surprised when he realized that Seto was actually a really good friend. He listened to the blond when Katsuya complained about something and added his comments here and there or tried to figure out a solution that could help the blond. It went that well that they both didn't mention the end of this one week and continued the way they behaved after that. And after a few weeks Katsuya considered them real friends. He was surprised that they went along so well, Seto even started tutoring him. Katsuya was a bit shocked when he was offered the tuition but said Yes because he knew it was his only chance to get a good grade. But when he saw Mokuba the next time the kid told him that Seto tutored him because he was worried the blond wouldn't pass his tests or with close results. And as a result his new friend wouldn't be able to go to college and make something out of himself, and Seto knew that Katsuya wasn't dumb and could actually study everything he wanted. So the CEO went out of his way and spent every day one hour with Katsuya to tutor him.
This was the first time Katsuya knew the brunet really cared about him. The second time Seto showed he cared was when he found Katsuya in front of his mansion, beaten up and full of blood. But when he saw that the blonde has cried, too, something in his eyes changed and Katsuya was for the first time really afraid of his friend. He was just lucky that the hatred that arose in Seto wasn't directed at him. The only problem was that he couldn't lie to Seto, the CEO would see through it. So he told him everything, that his dad started drinking when his mother left, that he tried to quit but always failed miserably, that each time he drank they fought and sometimes his dad beat him. And then he told Seto something he never told anyone before. His only thought was that he had to tell it to someone otherwise he would go crazy. So he took a deep breath and said the words that always scarred him most "He raped me...". Before he could react the brunette held him close and that made him lose control of his emotions and he cried even more and screamed out all of his feelings.

After this night he knew that they crossed the line of being just friends but it didn't bother him. He couldn't remember when he fell asleep, he just knew that when he woke up Seto already organized everything: His dad was in rehabilitation, the bills were taken care of and Seto was his guardian until he was of age. Katsuya could just stare at him and it took him a while until the things he heard sank in. And as suddenly as he was hold last night he hugged the brunette and cried again, thanking him over and over.
When he moved in with the Kaiba brothers his life became much better, but not only financially. Because he had more time and could study more, his grades were even better then after the tuition. But he also took his time to choose an university and which subject he should study. After he reduced it to two subject he wanted to know what his friends thought of his choices and which one he should choose. And because he lived with Seto, the brunet was the first person he asked.

"If you should study law or business?"
"Well, since my grades increased I hope to get a chance to study one of them..."

The blond knew he blushed because his face suddenly heated up.

"I didn't mean that I think your not capable of studying any of them, I was just surprised. Knowing you the subjects and the jobs would be considered as really boring by you"
"Well, I know that I always said that money doesn't matter for me, but I want to be able to stand on my own feet and not rely on anyone. And for that I need a well paid job."
"You know that you can stay here as long as you want."
"I know, I know, but I would really feel better if I could manage my life without your help."
"Then I'd want you to study business."
"You want me to?", he was confused by the choice of words.
"Yeah, I mean, losing someone as good as you to law or another company would be a waste, I want you to work for me."

If you ever thought that you knew how a serious Seto Kaiba looked, you were wrong. Katsuya haven't seen him this serious about anything before. The mood was really awkward because the look he was given made the blond feel as if Seto proposed to him instead of offering a job.

"Well, that's..., wow!"
"You still have time to make your decision, don't rush yourself."

Katsuya was glad his friend understood his confusion and smiled at him.

"Thank you, Kaiba!"

And then he was given one of the rare smiles of Seto Kaiba.

"You're welcome. But please don't take too long, you know how impatient I am."
"Haha, OK, I'll keep that in mind."

If Katsuya have looked at Seto at the moment, he would have seen the loving look he was given by the CEO.

The next step in their relationship was when Katsuya received the response from the universities. When he got the responses from all the universities he had chosen, he and Seto sat together to open them and help him decide to which university he should go.

"Are you ready?"
"To be honest...no...", the blond smiled nervously.
"Don't be nervous, I bet you got many promises."

A hand was placed on his shoulder and Katsuya relaxed a bit.

"OK, well then..."

An hour later both of them sat in front of six promises and two refusals. And five of six promises were business.

"Your choice?"
"You know how you offered me to work for you when I'm finished?"
"Of course, you know I don't forget important things."
"Well, I thought about this and..."
"Yeah?"
"I accept!"

When Katsuya turned to Seto to give him a sincere smile, he was greeted with a pair of lips halfway. But as suddenly as they kissed the brunet parted.

"Sorry, I didn't mean to! I rushed, please don't panic!"

But his blond friend could only look at him wide-eyed and confused, gaping at the same time.

"Man, I really shocked you, hm?"
"I... I..."

A smile placed itself on Seto's face and he took Katsuya in his arms.

"Please don't be mad with me. I just couldn't control my joy. I really don't want you to leave me and Mokuba, our lives became joyful. Mokuba considers you as his other brother for a long time now."
"This kid is just too cute for his own good."
"And I- I don't want to be separated from you longer than needed. I don't want you to leave me. I know it's a selfish request, but please stay with me. I will restrain myself and not jump you."

The blond laughed a little.

"Somehow these words just seem so unreal, hearing them from you."
"Believe me, I didn't want to tell you anything because you're my friend. But well, as I already said, my joy won over me. And you now that I actually don't act on my feelings."

And as a little blush grew on the CEO's face, Katsuya's heart skipped a beat.

"So you say you like me or love me or something?"
"Something..."
"Seto Kaiba, I'd be glad to stay by your side."

When he was kissed again, the blond put his arms around Seto's neck and pulled him closer.

"Thank you, Jou."
"Now you have to call me Katsuya, Seto."
"Your wish is my command."

So here he was six months later and laid in this big bed beside a sleeping Seto Kaiba who hugged him so tight he could hardly breath. But he still could move and so he reached to Seto's face to brush some of the hair out of his face. And because he knew the brunet so well he expected what happened and his hand was taken just as he wanted to take it back.

"Can't you sleep?"
"I just have a lot on my mind."
"Mind telling me what?"
"I'm just a bit confused... I mean, you saw the articles they wrote about us."
"I told you that this would happen when we make it official."
"I know, but I don't mean the fact that they wrote them, I mean what they wrote in them."
"Don't take this to your heart."
"But I can't, I just can't ignore it!"
"Should I shut them up?"

That made Katsuya giggle.

"No need to, just answer me one question."
"Which one?"
"When we started this whole thing and I asked you if you liked me or loved me or something, you answered me 'Something'. What does something mean?"
"Look me in the eyes, Katsuya."
"Hm?"
"I love you, Katsuya Jonouchi with all my heart. And I don't know if I ever will be able to stop this feeling. So if you're not sure you can endure me for the rest of your life, please- Hey, hey, don't cry. Why are you crying?!"
"I'm just so happy, I wanted to hear this so bad."
"Silly, you really wanted to hear me say it?"
"Yes..."

Seto positioned himself over the blond and looked straight in his eyes.

"I will tell you this everyday from now on for the rest of our lifes if you are willing to."
"What a stupid question, you idiot."

Sealed with a kiss, Katsuya Jonouchi suddenly knew why they were together. Their simple reason was love.

Hey, look what I've found on my laptop Oo

Have fun ;)