If I may be so bold: I think you're running into an
X/Y problem. There are stories on here with many installments, well-developed characters, etc., which just happen to integrate bondage elements; and there are stories that are basically the bondage equivalent of porn, actual fucking optional. Either approach is valid [1], but very different to actually write - and backstory is one of the ways, and I suspect [2] that you're not quite sure where you want to fall on that spectrum.
[1] As much I personally
prefer the former...
[2] Of course, I could be barking up the wrong tree. Read this as "food for thought" more than a diagnosis.