Yes, they were twins. Fraternal twins, maybe, but twins, nonetheless. Just because they were born on the same day doesn’t mean they were close. It was quite the contrary, actually. They were too different, with different values and thoughts towards everything. Jaejoong was smart, not afraid to speak his mind, but respectful if it came down to it. Yunho was rebellious, kept to himself, and resented anyone who dared talk down to him. And though Jaejoong avoided his younger brother like the plague, never speaking to him for fear that Yunho would hate him, he still managed to do something wrong.
What, you may ask, did he do? He was Jaejoong, plain and simple. So Yunho resented him. He hated his high grades. He hated his obnoxious friends. He hated his charming smile. He hated his caring demeanor.
Yunho hated him so much, in fact, that he couldn’t let anyone else have him. Jaejoong, his twin brother, was his, dammit. His.