Natsuo and Youji probably seemed just a little bit off to most people. So full of energy and immeasurable amounts of malicious intent for such small and adorable beings. Even to their fellow fighters and sacrifices, they weren't normal. The didn't have a name that belonged to only them. There was more than one set Zero's.
They fought dirty, easily resorting to physical attacks in the midst of a spell battle. Vicious and merciless physical attacks, at that. They had been manufactured, and they had been manufactured without the ability to feel physical pain. They, therefore, liked to see how others reacted to the pain that they couldn't experience themselves. Generally, they were viewed as just a wee bit insane.
They didn't think they were insane, though. They had each other to sympathize with, another who shared their each and every problem, and because of that, they seemed entirely in good mental health to themselves and each other. How could they be crazy when their partner felt the same way?
My cat isn't crazy,
The Zero boys spent nearly every moment of every day with one another. They had been together for as long as either could remember. If they had been apart at some point, neither found it to be a time worth having memories of anyway. They were made for each other, destined to be together, and they meant the world to one another. To them, their existence began with the other boy, and would end with the other boy. It was as simple as that. Any time that they hadn't been with their partner must have been insignificant, and as long as they were together, everything would be all right. They drifted to sleep every night, tangled affectionately together and thanking whatever gods or goddesses there may be that they needn't ever be alone.
He's everything to me,
Youji and Natsuo were a general pain in the ass. If they thought it would amuse themselves or each other to do something, they would do it, and to hell with what anyone else thought about it or whatever innocent bystanders may get hurt in the process. If they wanted to rape poor virgin teachers, they would damn well try. If they wanted to wreak havoc in Soubi's apartment and drink all the beer while they were at it, they did. If they thought it would be fun to go into a catholic church, grope the alter boys and piss in the holy water, good luck to anyone that tried to stop them. They broke whatever rules they pleased, no matter how large or small said rules were.
My cat burns the bible,
Together, they spent most of their time trying to get whatever entertainment out of life that they could. When you nearly kill yourself in spell battles on a regular basis, you try to enjoy existence when you can. They did whatever it took to be occupied and content. This usually meant pain for someone else, but hey, life isn't fair and people really ought to get used to it, right? Right. Others' anguish was their pleasure, and the pleasure of themselves and their partner was all that mattered to the Zero boys. So when they smashed a toddler's sandcastle at the park, or slashed someone's tires, they grinned at each other and laughed in appreciation of both their victims despair, and their soul mate's amusement.
And he thinks it's so funny.