I'll just throw a handful out to see if any catch your interest.
>Naga/Human
Some setup (war prize?) forcing a human guy to be the personal servant of a Naga. Perhaps some feminization as the Naga want's him to be a cute, presentable maid?
>Arachne/Human
Bondage, orgasm denial, verbal domination and degradation.
>Alp/Human best friend
Might not be gay enough, but I'd still like to request it. You could do relatively standard shy Alp who's still somewhat in denial about what she is, or more aggressive "you're gonna fuck me" Alp who wants her friends cock.