He is a warm-hearted guy with a painful past. He was often abused by his father and his only friend was a girl, whom he can't remember. Through his traumatizing experience and deep guilt toward his childhood friend, his mentality was broken into pieces, it erased the bad memories and created more personalities inside his mind as substitution.
She turned out to be Daniel's childhood friend, but can't remember as her memories were partly lost. At first Candice came to help Daniel because of sympathy but their feelings grew and together they start to remember their lost memories from their dark childhood and overcame Daniel's DID.
"So he held out his hand and Candice felt a frigid touch of his hand. They were holding hands, and Jace had clasped his hand tightly on hers. It was as if he was saying not to go away."