Grocky predator/prey play idea
So, the idea that humans are persistence predators while eridians are ambush predators is a horse beaten to death, right? Well, it's still twitching, so I'll beat it just a bit more.
While Grace could, very well, just follow Rocky until his little rock friend is too exhausted to continue to the point he just collapses, and that is a very tempting idea, there's something else he wants to try.
He doesn't tell Rocky what the chains are for, or why it almost resembles a bag, but Rocky trusts Grace implicitly, so when Grace reassures him he will like the use he makes of the chain, Rocky makes it for him.
And oh, how perfect he made it.
Grace still had to chase Rocky, of course. Just enough time that the eridian had gotten... sloppy. Overlooking details like xenonite Just barely sticking out of the sand inside a cave Adrian was oh-so-kind to add to the biodome.
And now, he was trapped. Inside the xenonite net with all five of his legs dangling down between the gaps in the chain, leaving him exposed and vulnerable.
Grace took his time walking up to Rocky, humming his eridian name in a low tone that he knew drove his mate insane, circling like a proper predator.
"You know," he started, taking off his glasses to put one of the temple tips between his teeth as his eyes roamed over Rocky's trapped body with hunger and lust, two emotions so close in that moment they could've been just one. "Remember when I told you you kind of resembled a crab?"
Rocky didn't reply. Grace didn't need him to.
"Well, there's something I didn't tell you about that," he produced something from the corner of the cave, buried beneath the sand. It was a piece of xenonite, rectangular and thin, but also unbelievably sturdy. Almost like a paddle. Resembling a ruler. "Humans eat crab."
*tap tap tap* went the xenonite, smacking ever so gently on Rocky's ventral seam. Rocky, meanwhile, wasn't speaking at all, simply making nonsensical, high-pitched sounds that sometimes dipped out of Grace's range of hearing.
"You wanna know how we do it?"
No reply. This time, Grace wanted one.
The sound that escaped the eridian was so loud it almost made Grace wince, but he didn't, simply managing a soft smile as Rocky babbled a sloppy "y-yeeeesssss..."
"Good," the human hummed, returning to those rhythmic taps that Rocky seemed to relish so much. "We crack them open and eat the soft, wet flesh inside."
Rocky stiffened. The words left Grace's mouth with a gentleness that did not match the meaning of his sentence and the eridian almost wanted to ask him to repeat himself, to confirm that he hadn't interpreted right such a disgusting practice. That he wasn't being compared to a creature that would be subjected to such a horrible fate.
But his ventral seam was cracking open.
"Oh, you like that, huh?" Grace stated, his voice a mix of smugness and awe as he nudged the tip of the xenonite just barely into the hole, leaning back to get a better look at Rocky's shameful display. "Disgusting. I'm telling you what we do to creatures like you on earth and you're getting turned on over it. Maybe you'd like that. Would you, Rocky? Would you like me to crack you open and eat you whole? Get alllll the soft flesh inside you in my mouth and find out how you taste? Is that it?"
With every word, Grace allowed the xenonite paddle to sink little by little inside Rocky, the rectangular form too thin to properly stimulate his pleasure spots. It was torture. It was ecstasy. He was more disgusted and scared and turned on than ever, and the vibrating of his body, the dripping of Mercury, and the cut-off, tuneless sounds escaping him left all that out in the open.