Topics/themes/tropes (kinda general, not only one fandom specific):

• noncon
• whipping
• language differences as a plot point
• D/s that feels natural, not roleplayed
• sadism/masochism. Again, see above for how.
• hair-pulling
• kissing
• open or half-open shirts
• gradually finding safety in each other
• dealing with the aftermath of noncon/abuse