Light
He'd been a Cenobite for almost a century before he had met Kirsty.
He was indifferent, cold, unfeeling, and calculating. He'd had plenty of chances to manifest the same for her; yet when he was around her, she would temper the darkness that had utterly enveloped his soul so long before her birth.
He'd been weary, bored of his dark existence...then she came along and lit up his entire world.
For some incomprehensible reason, she had the ability to calm him and bring out the best in him. Whilst she ultimately grew darker with each exposure to him, he would grow more human...at least in thought.
Without realising it, Kirsty Cotton had become the light on the dark side of him.
Pssh. If only Kirsty had been present during the events of Hell on Earth and Bloodline. She would have dealt with his crazy ass just by simply being in his presence. XD Seriously, though, it is headcanon to me that Kirsty would have this calming affect on Pinhead. :3