I don't think we've actually seen how the m/m sexual pairings play out as the sex scenes during EA have mainly been "Under Construction". Though I believe that in an earlier patch there might have been an early sneak preview of the Astarion scene, I've not seen it myself. And we saw a version of Halsin and Astarion in the recent PFH, but of course it cut away before anything "interesting" happened.
There was mention in the latest Community Update of romance as The Dark Urge which referred to liking bondage, which I'm guessing might mean that if you play as that character (you can't recruit them as a party member) you might be able to shape a D/S relationship of some sort, but that's pure speculation at this stage.
