Due to the customary belief that twins were an omen, Fay had lived in isolation with his twin, and being identical, the both of them would go out in turns, to take care of their sick mother, and try not to cause attention to themselves since their personalities were radically different. The king caught wind of this and had their mother executed for betraying the king and the twins cast out of the city, into the cold winter province that surrounded the little town. The both of them were found by Ashura that morning and rescued. Ashura took both Yuui and Fay under his wing and they lived with him for many years. There was a new king on the horizon at the time both Fay and Yuui established a strange ability, and Ashura feared what the king would do if wind was caught of his son.
Or so he said. The both of them were still to young and much to naive to realize that in Ashura giving up his own life force in order to put a seal on them in the from of feline ears and tails (Yuui an orange tabby and Fay a gray tabby), that he was making the twins stand out even more (after all, they would be the only two in Celes now with those appendages, but they were made to believe that those ears were to keep their abilities in check and kept hidden). The twins were able to live peacefully for a few more years before Ashura died and then Fay was forced out of the little home by depressing memories that plagued him, and unable to be apart for long Yuui followed.
Fei Wong Reed was this new king, in alliance with the sadistic Ashura. After Ashura's death he sent out his goons to capture the roaming Fay and Yuui, and unfortunately he succeeded. First thing he did was play with the spell on the twins ears and tails, making them magical amplifiers and thus giving them much more magical potential. Fei Wong used the restricted dark magic to do this and then proceeded to try and teach Fay and Yuui it. Unfortunately Yuui gained a much better understanding of it since Fay was much too soft and innocent for such horrible images and things. Fei Wong hated this about Fay, and a couple years later he had the other put to death by torture. Yuui of course found out, and tried to rescue his brother in any way he could. He as too late, but before Fay could pass Yuui stole his soul, and sealed it in a piece of fluorite given to him by Ashura a long time ago; keeping Fay alive by his heart. After, Yuui changed his name to Fay. He vowed to destroy Fei Wong, but he would need to be much more powerful then that. And so, another couple years after his brother’s death, he became the keeper of the restricted dark magic, which earned him the high-ranking title of "D".
During those years though, he started having strange new developments of powers. His magic was no longer the same. It seemed to come from something so much darker and more dangerous. And Fay began to see people and hear things that were not there or no one else heard. At times he wondered if he was insane, but ignored it to the best of his ability. He was twenty now, and so much stronger then when he was a child; a real force to be reckoned with. Now the strongest and most deadly of all magicians in Celes. Fei Wong used him for his evil plans for war. And Fay conquered all uprisings and other armies almost single handedly. He was the installer of fear and kept the rebels in submission, and he stood quietly by his king's side. Eventually the whole continent was over run, and Fei Wong renamed it Valeria.
Unfortunately a lot of horrible things had to happen during this war. Fay killed thousands of people in grotesque ways (including a soldier, named none other than Kurogane Youou, he fell deeply for who was trying to build a resistance; when Fei Wong found out it was a rather depressing end. Unfortunately, Fay could not grab this soldier’s soul before it passed, and so lives with a deep regret for such a failure). And, now that the war was over, Fay found himself seeing things and hearing things even more. It did not take long for the connection of death and dark magic to connect and for Fei Wong to find out. Fei Wong wanted to use his power for his own greed, but Fay refused to tap into this strange new ability he had required. Fei Wong tried to force him, and Fay found during this point he could over power his king.
And so he did just that, destroying the evil dictator and then making a run for it. It was his way of redeeming himself one could say, since the people finally were able to break free of anarchy and create something a bit more for people. Fay however, stayed to himself. Two years later his ability had grown much stronger, and he realized he was very haunted by the spirits of people he had murdered. Some were angry with him, and others full of sadness. Fay made his priority in life to help them all pass on, and every other one he happened to come across. However, he will not give up on his brother, and he still searches for a vacant vessel to bring his brother back from the dead. Quite literally.