Vadoma's Sorrow
Draco made no moves to stop her or absorb her anger. As dark and wicked as it may sound, he felt that this particular development was extremely good for her.
When he had been a 'good guy' in his past life, things had gone well.
However, he only rose to power after all his negative emotions erupted and he fell into the dark. One could say that his negative emotions had been strengthened due to the remnants of his bloodline, but it was crippled back then, and far too weak.
If Roma experienced an intense wave of genuine hate and anger, it would forever change her character into something he preferred.
Once a person fell into the dark, they never truly escaped. They just experienced bursts of light as they clawed their way back up.
Even Draco, who had cut off his hatred and anger in this new life, who had everything looking up and extremely promising for him, was still strictly a villain.