In the beginning he really had no control. The feelings of attraction he had towards her were barely understood by him, so needless to say he confused the hell out of Teru. He had once pulled her in close; less than three inches to her face, and asked her what she would do if he was Daisy. Thinking about the incident now still brought a faint blush to his face.
In the beginning, right after he met Teru (or abducted, whichever) he had fallen fast. Her commitment to her friends, her brave and intelligent nature, and her compassion for Daisy overloaded his senses. Even though she had been the only thing he had thought about for the last few months as Daisy, the way he thought about her now was different.
Master teased that he had fallen in love with her (the bastard knew him far too well), and, Kurosaki supposed, he did. But even now, as Teru was discharged from the hospital and things seemed to fall into their normal places, his feelings were changing.
He had loved her as Daisy, a protective sort of love. She helped him through the days after her brother's death as much as he helped her. He had loved her as a friend or brother.
He had loved her one-sidedly, and had resigned to the fact that while he would never be with her, he wanted her to be happy. His goal was to keep bullies off of her, to fulfill her requests from Daisy (though far and few between) and to keep her smiling. The way he had to treat her to safely be close to her made him feel guilty, though. He would tease and torment her to hide his true feelings underneath. Even after he learned that she loved him, he couldn't imagine being with her. It was too absurd. Truly, he didn't deserve it. For his past sins, and for his role in her brother's death, it was unthinkable.
Riko planted the idea in his head first. She told him that Teru was there whenever he was brave enough to reach out to her. If he wanted, he could be with her.
The polarity of this idea compared with what he had decided to accept as his fate shocked him. Could it simply be that easy? Reach out and she'd be there? Wasn't it wrong of him to wonder in the first place?
But now his love for her was slowly evolving yet again. He didn't want to simply know she was content with her life, and to see her smile from afar. He wanted to be next to her, be the reason she was smiling. He wanted her to know his feelings, wanted her to understand that he felt the same way she did.
He wanted her, so badly that it hurt.
He was sick of pretending to be the heartless bastard janitor, or hiding his happiness or embarrassment behind gruffness. He wanted to be the gentle person he could be around her (though usually when she saw his softer side she worried that he was sick or the world was ending).
But, even though she had her arms wide open for him, he couldn't do it. He refused to be with her if she didn't know the truth about her brother's death. He was too scared that she would never want to see him again after he told her the truth. So Kurosaki clung to their normal relationship, feeling both the weight of longing and fear pushing and pulling him in different directions.
Because in this world he feared her the most, and in this world, he loved her more than anything else.