One time, multiple, or forever?

What's your favorite scene frequency? Do you prefer imagining a one-time affair, where it happens in one encounter and then is done? Parties separate and go their own ways to relive and deal with the trauma (or be forgotten).

Or do you prefer multiple-incident fantasies? The traumatized is someone who can be encountered again or is in a situation where liaisons may happen multiple times at the initiator's whim.

Is it a forever affair where they kidnapped, concealed, and spirited away for permanent free use?

What does it look like?

More importantly, why? Why does this fantasy appeal more than the others?