Have her grow over time, while mental changes that take effect the larger she gets.

As much fun as it would be to just turn Sarah into an enormous giantess to start with, Tom knew that wouldn’t be the most satisfying way to approach this. So instead, he made a different kind of wish on the coin. ‘I wish my wife will start growing taller, larger. It will start slow, at just a foot in a week, but in will keep escalating until she reaches her maximum height, at a thousand feet tall. As she grows taller, her ability to care about the well being of people smaller than her will go down, and she’ll become more interested in using her size to dominate them. She won’t ever actually hurt me, even accidentally.’

With that wish made, it was really just a matter of waiting. It only took a few days for him to notice she change to his normally short wife, as she gained a few inches. It wasn’t until the near the end of the week, when she was matching Tom’s six foot height, that she started to realize something was up. “Do I seem taller to you, Tom?” Sarah asked over dinner, eye-to-eye for the first time in their relationship.

The coin in his pocket, he realized he hadn’t actually prepared for how she would react to this situation once she noticed what was going on. ‘I wish Sarah will believe any explanation I give to her for anything weird that goes on.’ That done, he confidently lied to her, “I heard something about some kind of second puberty thing, some people are starting to get it lately. It’s just your body going through another growth spurt.” The effects of the growth on their relationship didn’t really start showing until a few days later.