Bisexuality is a spectrum, and everyone is on it

To have two beautiful naked women in the same room, it seems a shame not to indulge in some experimentation. You move Cira away from the bed, plucking the sheets from her grasp and exposing her breasts again, and set her down next to the diviner.

You bind their hands behind both their backs using some of the discarded underwear, and take the diviner's robes, which you tear into long strips of cloth. Now the fun bit: you push the women together, face-to-face, nipple-to-nipple as their boobs are mushed against each other, and wrap the strips of cloth around the pair at their waists, so they can't move away from eachother.

You walk away to stand a little behind Zed, and watch.

A chorus of startled gasps and high-pitched squeels, as the two elven women find themselves pushed up against each other, grinding their breasts and privates up against one another and practically banging their heads. When they struggle with the bonds, they simply rub up against each other even more.

"Zed! Don't just stand there you fool! Untie us!" Cira yells.

You see Zed is shocked and surprised, and he's about to step towards the wrapped pair - to free them presumably. You put your hand on his shoulder, stopping him, and go "wait, wait, let's see where this goes", as if you're some college frat talking to a friend while observing a make-out session.

Zed actually momentarily forgets himself and stands back to watch, before both women angrily reprimand him in unison, as they wriggle in their bonds:

"ZED!!"

He snaps out of it, realizing who just spoke to him, and pivots towards you, drawing his blade with a flourish.