I'll chirp along with the chorus that Trust is a Must!
Especially for someone with the odd dual-natured "Horror/Love" of the whole idea, like me! When I was little, I used to lay awake, skinny arms and legs stretching towards the bedposts, and imagine what it would be like to be trapped like that, with the kids that I disliked humiliating me. Or worse, the idea that a boogeyman/woman might attack in the night in a similar fashion.
Oddly enough, with the onset of puberty, the idea of tying and tickling someone else really took hold. Before that, it was always, How long could I stand it?
So, from early on, the concept held alotta dread for me, but a weird fascination, too. Being bound, gagged, and tickle-tortured is an almost spiritual/cleansing ritual for me. The few times I've been fortunate to experience it with someone I trusted that much, it was both better than, and worse than expected. A whole range of feelings and emotions can sweep over you. It's a very cathartic experience.