Kyoya watches Tamaki from the shadows. He spends all day trying to inconspicuously keep track of the overdramatic blonde. He does not know why his eyes are always drawn to Tamaki. He just knows that he can't look away. He knows in his heart that if he looks away and misses something he would have a hard time forgiving himself. Tamaki is a ray of sunlight in his otherwise dark existence.
He finds himself thinking of Tamaki at such strange times. Like when he is in the shower. Or even when he is eating a simple meal he is sometimes reminded of the blonde's overzealousness over what he terms "commoner" foods. He also thinks of Tamaki in not so strange times. When he takes over his father's company he finds himself thinking of him and how proud he would probably be if Kyoya ever told him what he had done.
Kyoya watches Tamaki and Haruhi together. He thinks to himself that he had better keep track of his expression lest they both realize how jealous he is of the blonde king and brown haired girls relationship with each other. He wants to say something to Tamaki but doesn't for fear that the smile on the blondes face would suddenly not be directed towards him anymore, and he knows that he needs that ray of sunshine to carry on.
Things in to Ootori household are tense. Always. Kyoya never has a moment of leisure time. There must always be some sort of motive behind everything he does. He wishes he could be carefree and without guiles as Tamaki. He knows such a thing is impossible for him though because he must always be one step ahead of his father and brothers. He must always be thinking three steps ahead so that he can finally be free of them and make his own way. So that one day he can garner the respect he deserves from them.
Kyoya doesn't admit this to himself, but he loves Tamaki. The couple of times that he thought about it he immediately buried the thought in a deep and dark hole somewhere in his subconscious. He pretends he doesn't know why he feels jealous of Haruhi, or even the twins. He pretends to be annoyed with Tamaki and his penchant for calling him mommy and himself the daddy. When really it gives him a nice warm fuzzy feeling in the pit of his stomach that he hasn't ever felt before. He likes to pretend that he doesn't see Kaoru's pitying glances or Mori's knowing ones.
On the night of Haruhi and Tamaki's wedding Kyoya gets drunk. Drunker than he has ever been before and will ever be again. He goes home to his dark house and for the first time ever cries until he finally passes out in a drunken stupor. He cries for himself. He cries because he knows that now its over. There is no chance for himself and Tamaki. Not that there ever was one he tells himself. The next morning he wakes up hung over but somehow pastes a semi happy look on his face. At least as happy as the shadow king ever looks. He makes himself hug Haruhi and Tamaki on their send off for their honeymoon. He makes himself wish them congratulations. He knows that if he doesn't then the look on Tamaki's face would dim and he knows he wouldn't be able to forgive himself for dampening this moment for them.
Kyoya is observant and he thinks he knows many things. He is intelligent. More intelligent that most. What he doesn't realize is that for as long as he watched Tamaki from the shadows Tamaki has also been watching him. He doesn't know that Tamaki's declarations of love were actually genuine. Just wrapped up in drama and theatrics just in case Kyoya did not feel the same. The blonde had already been left behind and rejected far to many times. Tamaki knows that if Kyoya ever looked at him with the same eyes that his grandmother used to he doesn't think he could ever quite recover from it.
Years later after they are both married with children they sit and stare at each other with want hidden in the depths of their eyes. As their wives sit and chat together about mundane things Kyoya and Tamaki communicate silently. They share hidden looks and touches. It never goes further than that though. They both made their beds and were too dense to notice what the other was feeling. Tamaki is Kyoya's sunshine and Kyoya is the strong dark presence that helps Tamaki carry on when he would otherwise feel to weak to do so. Years later when its much to late they both realize what they missed. Then they look at the people surrounding them. Their laughing children and smiling wives. And while they miss each other and both secretly, silently, mourn what could have been; how could they change what has already been? So Kyoya continues to watch Tamaki from the shadows. The glint of his glasses flashing when he hurriedly looks away the only clue.