Both of them knew that they couldn't stop finding Chaos' shattered souls, to be able to suppress the darkness inside of him, as it would also give him strength.
Therefore, instead of preventing himself from using his own power, it would make more sense if Chaos himself became stronger in order to overpower himself.
"This will not end like this. We will survive this," Chaos promised against her hair, as he hugged her tightly and kissed her temple.
This was the strongest feeling that he felt for her, strong enough for him to want to be with her, regardless of the consequences he had to face.
It was strong enough for him to not care about anything else but her.
It was her and always would be her, since the very beginning.
His very existence was always for her...