Have you considered combining slave!Reinhardt and Reindatta? The omnics won the war and Reinhardt is a captured soldier given to Mondatta as a gift. Mondatta is against slavery and vows to never use Reinhardt but other omnics disapprove of his human sympathizing and make him dominate Reinhardt in public. The poor noble, repressed nerd gets totally overwhelmed by pleasure and ends up smitten with Reinhardt.