Initially, Harvey planned to let Rachel kill Aiden as a pledge to him.
However, he never imagined that Aiden still had such insight and vision.
Still, Aiden was right.
Even if Rachel entirely succumbed to Harvey, Oliver’s death would still remain as a thorn between the two of them.
Perhaps she wouldn’t do anything under normal circumstances, but she might lose control during critical moments.
The best solution was to have one more person beside her. For instance, Aiden Bauer. In this way,