I'm pretty sure his back story was shared. He was scared of his dad because his dad would prostitute his mother to alphas until the day she ran away. He looked very similar to his mother and his dad made a comment one day basically saying "if only you weren't an alpha, you look very much like your mom" which made Hyesung believe if he was found to be an omega his dad would also sell him off to alphas. It's why he was so obsessed with being an alpha and not an omega.
They already did. His mom was used as an female, omega, cum rag for his father to get up in ranks at his company and he would beat her if she didn't do what he said.
She left Hye and his father to go live her life but at least she said bye to Hye.
His dad was big on looking good so he wanted Hye to be of some use since he thought he was an Alpha. But it turned out Hye was usless to him, so he'd just bitch and whine about how he was wasting time and money on Hye and if he was an Omega he'd be at least useful.
So Hye dropped outta High school and home, working random jobs to get by. fast forward to now.
He was still spoiled as a child, he would just see his mom get her ass beat and cry alone. He just got verberly abused by his dad when he was in his teens and that's why he is scared to be seen by his father as an Omega. It could have been waaaayyy worse for him. Especially since he is a recessive Omega.
Guys am I the only one who still wants HYESUNG'S BACKSTORY. Why he was so scared of his dad and his mom leaving him must play a big part in his really bad personality at first. IF THEY END THIS WITHOUT HIS BACKSTORY I'M STARTING A RIOT