"Tie them up together?"

The woman stammers with incomprehension at this strange circus she's inadvertently wandered into, thinking really hard to produce an answer that might be satisfactory to you, before finally managing to blurt out "Uhm.. tie the two of them up together?!"

You lean back, contented. "You could've phrased it with some more elegance, but I like the idea, sounds kinky."

Evellyn manages to say "By the goddess, no! Don't you dar-" before time stops. You retrieve a little bit of extra rope, start going through the familiar routine of slipping off Evellyn's clothes, and then when she's nice and nude haul her off her perch and plop her on top of Vanessa's back, legs astride the barrel like she's riding a horse. A burst of ropework activity later and you have her fully secured so she can neither fall off nor move her limbs much, with a couple layers of rope twisted around her stomach to push her arms up against her torso. You finish it off with a strip of cloth to gag Evellyn, like a cherry on top of a master cake.

Time resumes, and at the sudden violent burst of motion the guard falls to her side on the ground, looking up at the masterpiece produced at her direction. Evellyn wiggles helplessly across Vanessa's back, and Vanessa lets out a muffled protest at the sudden weight placed on her back, before starting to submit to the sensual feeling of her back being ridden by an equally naked partner. Just because Evellyn's struggles are to no avail doesn't mean she's less pissed about it, and she exchanges a withering glare with the guard on the ground, who recoils.