I'd like to invite you to Another Realm to ask this very same question.
Sometimes, a person will feel something is "missing" and it might not involve fetish or alternative play. Perhaps it's a feeling that you're missing?
So often, as others will share, being "alternative" could be as simple as rubbing different types of materials (and fur!) over your body and your private areas.
Just a soft and sensual sensation play. Or you might like to be teased until your back arches and you cannot stand it.
There are simple ideas to try first (a teasing and elongated blowjob with some anal play?) that I don't consider a fetish at all but some might!
When you're laying in bed at night and your thoughts are slowing down and they turn to sensuality, what do you think about?
What I think about is pretty extreme and I wouldn't wish to actually do what I'm thinking of. However, sometimes I imagine a few prettier situations as well.
Find out what YOU might find intriguing and then contact someone who seems as if they could fulfill that desire.
And then come back and tell us EVERYTHING!