Valentin was born with a hunchback and facial deformities. Being backwards sociopaths, both Helena and Mikkos would not accept a baby that was not perfect. They would have felt a great deal of shame. When Helena gave birth to Valentin, she passed him off as being Mikkos' bastard son, the product of one of his affairs. Helena and Mikkos played sick mind games all through their marriage, she knew having a less than perfect son would devastate him. Mikkos hid Valentin away and disowned him. Helena had the satisfaction of knowing she caused her husband such distress. It did not matter to her that it was her own son that she abandoned, she got rid of her "shameful deformed" baby and mentally tortured her husband at the same
They were both such heinous creatures.
Helena was so afraid of Valentin because he was HER son and she knew what he was capable of. I am making a guess that Faison was his father. Valentin had the crazed vengeful sociopath gene on both sides. Helena knew Valentin worked for the WSB and the DVX. He also had surgerys to repair his spine and face. He was a new man locked and loaded for revenge. Helena did not fear anything or anyone. However, she knew she created a monster in Valentin and he terrified her.