I'm sort of having writer's block too, but I think I have a few things to add. Since Minhyuk (Bbomb) needs a destructive past how about making his family show hatred to him?

Let's just say this:

From the day he was born Minhyuk's family has shown nothing but hatred towards him. They wanted the boy to die when he arrived in their home, but the only two people who wanted him alive was his older sister and best friend. When the boy was two years old he was abused by his father - who was an alcoholic and always came home to stir up some drama with his son. His mother was a e who didn't really care about her poor family. She was just in the business for the ; which is why a year later when he turned three she died from an aggravated assault from one of her customers.

That's the only thing I have for past I think >.< Sorry if its not helpful.