Reason For Insanity
Kabuto was, in all cases and medical proof, was mentally unstable. That was the word he would use for it. As if a more medical term would stop it from meaning insanity. It was not his intention, of course, as Yakushi Kabuto was perfectly fine with his insanity. It did not stop him from his work. What bothered him, was that people thought it was caused by Orochimaru.
Maybe it was, by some roundabout way.
A spy since he was four, Kabuto managed his task without anyone ever questioning. From a child, to a teenager, he pretended to grow up just like every other child in Konoha might. He was perfect, absolutely perfect, at being imperfect.
Kabuto inwardly hated being seen as less then what he knew he was, but he dealt with those feelings accordingly. Because in each smile, he was celebrating the success of his work. There were the occasional days he wished someone would find him out, find everything out. And they would wonder at his ability of keeping it hidden for so many years. Those feelings passed quickly though. A fluttering thought which occurred maybe as he was blinking his eyes. Then he promptly forgot about it.
His grades were normal. Not the worst in class, he was still a far stones throw from being the best. And if anyone knew just how far Kabuto could actually throw a stone, using whatever he wished to bounce it off of without anyone noticing, that would no longer be the case.
Kabuto knew he deserved that praise which the other students received. He knew he did not deserve to be told, 'I know you have it in you to do this,' because he had already been doing it and never needed to have it taught to him again. Still, Kabuto blushed and completely flustered would try to right his attempt a few more times before making it just bearable. After all, it was an art and a science to be able to mess up correctly. Praise came in the form of Orochimaru, praise Kabuto would do everything in his power to gain and more.
The same went for home, all of these small feelings. Being the calm, polite, under-average, teenager was almost easier to pull off for the people who called themselves his parents then it was for the rest of his peers. Almost.
Until he went into his room.
One's room was supposed to be their haven from the outside world. Door shut, blinds closed, as long as evidence was rid of anything could be done. Their own personal space, which even parents did not pry into too much, knowing that a child needed one place they did not have to worry about anyone else in. This was not the case for Kabuto, returning to this room and seeing the mess he had left, as he had unknowingly decided his character to be before it became the problem. Why had he decided to make this a part of his character? There were the normal children who were tidy as a parent would like. He had needed a flaw. Now, it was too late. Changing a flaw was not an option.
Still Kabuto returned home and went into his prison, mind screaming to just dust one surface, or put the books back on one shelf.
But he did not, such a good spy, such a good disguise, and would lie in bed, mind screaming more to at least relax in one place. Maybe when Orochimaru would let him return to the Sound, this would no longer be his issue.
The insanity was caused by a decision Kabuto realized he would not be able to live with while sane. Caused by himself, which worsened the condition.
Needless to say, while he lived in Konoha, Kabuto did not sleep much.
I have Kabuto in my mind as a clean freak for some reason. It might not make any sense, but it proves just how good of a spy he is!