Sakura and Shirou
Sakura frowned at the Shaman's words, knowing that, unless they could come up with something fast, she would have no option but to submit to his demands. Yet, as she pondered the situation, she came to a realisation. Whilst she had assumed what he wanted was for her to perform sexual acts, that was not what he'd actually said. What he'd demanded was that she submit, that she prostrate herself before Steaven and put herself at his mercy. So, perhaps, his true desire was not sex, but power. He wanted to be in control, to have their lives in his hands.
The more she thought about it, the more it made sense. He was a child, and one who seemed to be somewhat neglected by his family. And, judging from the way they had met him, it seemed like his former bodyguards were controlling, desiring to limit where he could go and what he could do. And, as someone who had spent most of her childhood utterly powerless, she could understand the allure of being able to change that. She didn't need to fuck him, all she needed to do was give him power over her.
The only question, then, was what he would do with that power. Would he take advantage of her, or would he simply let her go? Seeing how he was now, Sakura was sure it would be the latter. He seemed genuinely distressed at their plight, and seemed to genuinely wish to help. And, even if she was mistaken, even if he did choose to abuse her, even if he did unspeakable things to her, nothing he could do would be worse than what would likely happen if she refused.
With that realisation, Sakura accepted her fate. She would indeed submit, she would put herself at Steaven's mercy and appeal to his better nature. But, even if she was willing to accept the Shaman's terms, she was not stupid. If she agreed, what guarantee was there that Shirou would be freed? Or, for that matter, that she would be forced to do as she had promised? She was willing to submit if it would save Shirou, but not if it left her no better off than she was now.
As she was considering her next action, however, Steaven spoke up, asking Nanako for help. That, plus the squirrel girl's reply, caused Sakura to hold off. After all, if he could truly do as Nanako was suggesting, then there was no need for submission. And, even if he could not, perhaps talking to him would give her the opportunity to butter him up a little and make him less likely to mistreat her. So, she turned to Steaven with a smile and spoke.
"I believe in you too, Steaven", she said. "The Shaman is part of you, surely you can overcome him if you try. But, even if not, even if I am forced to submit to his demands, I trust you. I know you will not harm me."
Then, she turned to the Shaman.
"Supposing I was to do as you ask", she said. "What guarantee do I have that you will release my husband?"