Cancer. When he first heard the word, he had been four years old. Yylfordt had been six. Little Szayel didn't know what the word meant, but he recognized that the doctors all looked very sad, and his parents were upset. He heard several words and learned to associate them with that single word of cancer: Aggressive, no cure, fatal, expensive. The doctors had explained to him that this word, cancer, was what had been making him hurt and feel sick. It was why his tummy hurt so often.
Yylfordt had been a godsend back then, caring for the younger Granz when their own parents wouldn't. Because the treatment was so expensive. By the time Szayel was ten, he was stuck in bed all day because the cancer had spread and left him in too much pain to do much more than read. When his head hurt and his vision got too blurry to read, Yylfordt would read to him. His brother was twelve then, and they had both been abandoned. Yylfordt would leave, usually at night while Szayel was asleep. Somehow, whatever he did during those long nights were enough to pay for Szayel's treatment. The medicines that helped him live longer, helped him with his pain.
At fourteen, they realized the cancer had spread to his brain. He was given three more months to live. He had bouts of madness, things that varied each and every time. Sometimes he couldn't stop laughing. At others, he became enraged at the littlest things. Sometimes he cried. He was sure that his brother would leave, just like their parents. He was hard to live with, and he wouldn't last much longer anyways.
But still Yylfordt would visit.
He survived past those three months, surprising the doctors caring for him. They hoped that maybe, just maybe, since he was faring so well so far, he would survive long enough for a cure to be found. But it was a long shot.
He still remembered the day that he died quite clearly. He had been hurting, no matter how many pain medicines they pumped into him. It was hard to breathe, incredibly so. He had felt so tired, having lived much longer than expected when he was first diagnosed at age four. Now he was seventeen, and much smarter than even some of the doctors taking care of him. It was what happened, when you had nothing to do but read all day and night.
His brother had just left for the night, to do whatever it was he did to pay for the medicine and hospital care. His eyelids grew heavy, so he shut them to rest some. The next thing he knew, there was beeping and doctors everywhere. His brother had been called back, to say goodbye. The last thing he remembered was smiling at Yylfordt, saying goodnight one more time while his brother cried and tried to read a bedtime story to him. Then nothing...
Now, Szayel wasn't called the Espada of Madness for nothing. Those bouts of madness, brought on by a brain tumor, still haunted him. They turned his amber eyes gold and made him act in unpredictable ways, causing him to be feared. He was alone, and had nothing to lose. So he let it happen.
But then he wasn't alone. His brother was here, in Hueco Mundo, just like him. He didn't ask about it, it would hurt too much. Instead, he fought the madness. To be with the one who never abandoned him, even after death.