It's an absolutely wonderful idea. Afterall, that's why we read stories. I also have a fondness for non-consentual sex and mind control stories. Also the occassional tentacle-beastie story.
In reality? That depends solely on the people involved. Regardless of the kink, I would not expect someone to acceed to my wishes without her knowing ahead of time that I had an interest and I knowing ahead of time she had one too. (Except no tentacle beasties...)
If something new comes up, and is discussed, sure. But not out of the blue. And certainly not as a "test" of love or loyalty. There's plenty of that demonstrated without having to exceed the submissive's limits.