Hm, alright.
Ezequiel's mother was always an oddball amongst the angels. Instead of purely hating demonkind, she instead found them curious. Why did they seem to be oh so sinful? She decided to study them, using the excuse that it would get them better information on their enemy. Eventually one of her investigations went a bit too far, leading her into Hell itself, where she met a fallen angel. This fallen angel seemed to be just like her, wondering about the angels and their blind devotion. The two decided not to attack each other, and got to talking. They eventually found a safe place to meet up, where they managed to meet several times and eventually fall in love with each other. Then they did the sex. The pregnancy of Ezequiel's mother soon became obvious, but she was unable to reveal the truth due to her fears of the other angels not accepting the truth. Ezequiel was soon born, and his mother did her best to hide his demonic half. Soon his wings were revealed, however. Most angels still don't quite understand, but those who do treat Ezequiel's mother with scorn. Contrary to his studious parents, Ezequiel decided to become like his fellows and prepare for the war that they all knew would happen. This is why he practiced so much with his blades and became such a strategist. Due to his parents still being his parents, he tends to be more about strategy and outwitting his opponents.
That good?
I mean, sure, but there's already an explanation of why they're sinful.
When Lucifer/Satan use to be an angel, he was said to be the most beautiful and strongest angel; both his strength and beauty outrivaled that of most other angels (if not all). Though, he was envious of Jehova. Lucifer wanted to have the same power that Jehova had, and be equal to him. Other angels who agreed with Lucifer joined him to rebel against Jehova.
Through their bitterness, a war happened between both opposing sides, the ones who sided with Lucifer and the ones who sided 2ith Jehova.
Jehova had enough of this, and he used his power to vanish Lucifer and his followers, altering their appearance in the process. Lucifer was hit the most drastically, and due to his change, his name was changed to Satan by Jehova.
Then the creation of Adam and Eve came along, the serpent possessed by Satan tricking Eve, who then later tricked Adam, and humanity was also in sin. Due to Jehova's power, however, he forgave humanity and sacrificed his son, Jesus to pay for the ultimate sin, the destruction of all humanity.
So, yeah. The Bible can get super confusing at times.