Size difference, , , shibari, power plays, spanking, choking, dacryphilia, somnophilia, cnc/noncon,  hair pulling, degradation, voyerurism/public , weapons play, group , abo, knotting, ion, sounding, edging, denial, dom/sub, dumbification, mindbreak, Stockholm syndrome, drugs, public humiliation I can't think of more atm but will add later I'm sure