Ensure she will never do something under a transformation that she would hate after it ends.

After a lot of thought, Sarah gave her answer. “I think...I’d prefer restricting what the coin can make me do.” She sounded conflicted, but resigned, and Tom could understand why. No matter how much they might love and trust each other, he could see what she might not want to wish away her ability to object to anything he wanted to do to her ever again.

So, holding the coin in one hand, Tom rubbed it and wished aloud, “I wish that Sarah will never do anything under the influence of a wish that she would hate herself for doing after the effects of that wish end.” It warmed up in his hand, and he knew it had been done. “Good?” he asked her.

Sarah nodded her head, and gave him a genuinely loving smile. “Yes. Thank you so much, Tom. I know you...kind of just threw away a lot of what you might have hoped for, using this coin, but I’m sure we can still have fun, even with that in place.” That night, they had loving sex without any influence from the coin (aside from the de-aging from the first wish still in place).

That done, they went to bed, and soon settled into their work week once more. Of course, this was no time for being idle, not really. It was, if anything, just a chance for them to think of more things they could do with the wishes. In fact, it seemed that more than him, Sarah had quite a few ideas. Tom based that assumption on the stack of notes on lined paper she put in front of him after they finished dinner in the middle of the week. “Notes?” he asked.

“You know me,” Sarah said. “If we’re doing this, we should do it right.” He started looking through the various ideas, and it was clear she really wanted to test how far the wishes would work. They’d already altered her age and her mind, but there were another avenues to consider. Could it give her someone else’s memories? Could it turn her into another species? Could she get superpowers from it? There was a lot they didn’t know, and she was ready to tell him the number one thing she wanted to explore next.