"I wish I could get rid of them."
"There's a procedure."
He rests his head on your chest, the smooth, hard, and cold exterior of his shell-like plating does not feel very uncomfortable.
"I know, but..."
This topic disturbed him as much as the act itself; his ability to pass individually large, globular, masses of sperm. An incompatible vessel, such as yours, would merely collect these undulating deposits of ooze. Your body would uncomfortably, but not unpleasantly, swell as though you were a basket filled with Easter eggs until they began to spill and slip out of you.
You were only aware of this by description and context alone, he had adamantly never wanted to try.
The two of you took on each other in a different way, him riding your strap until he could feel the beginnings. You could too for this much he was willing to show you. You knew where to feel on your own now but he had guided you the first few times towards the base of his bumpy and ridged shaft. It didn't look any different but if you squeezed you could feel resistance, it felt like a bowling ball concealed in a sock.
It was at this stage that you would thread the long, sterilized rod into the tip's slit.
His body would ripple, his mandible-like teeth would chatter, and he'd let out a soft gasp as you let gravity take over the long pin.
He was able to excrete an ooze of his own, as you continue to slowly run your hand up and down the length of him, you'd feel the mounting slime on the surface start to run in between your fingers.
He would grip the outside of your thighs tightly, sitting patiently with your dildo embedded within him.
"Twist it."
You kiss the crook of his neck before using your free hand to oblige, twisting the rod very gently. You'd whisper to him in a caution, "Don't buck," and it took him all of his willpower not to.
He lets out a whine, the sound coming of his plated face as a more muffled wheeze. You kiss him again, encouraging him, "You're doing such a good job."
You could feel at the base what was once firm and larger than a golf ball now felt like a popped water balloon. You continue to masturbate him, subsequent sperms that were behind the first would be immediately skewered and popped by the rod.
He said that he produced about six at a time; you had never seen it for yourself, or even one an entire one intact, because by the time you did it was just like thick semen with bits of tissue, the outer membrane.
His four-fingered hands were nearly white knuckling, you wanted to kiss the carapace on his chest.
If he were doing this to you, allowing you to be the recipient, you'd be able to.
No, you never suggested it.
You had early on but when he stormed out of the room in an upset, you knew it was a forbidden request to try again.
You liked this arrangement too, though. He liked that he was submissive to you, and he was, but you had a difficult time as seeing yourself as the counterpart. He trusted you enough to divulge that it felt too uncomfortable and disturbing to cum, that he never, ever, masturbated despite feeling intense arousal.
With him as the primary historian, you were able to find some resources and literature on this alien species' anatomy and reproductive cycle. Together you were able to surmise that if it was passing the sperms whole that felt horrible, that maybe you could pierce them before they exited.
And it worked.
"Please..."
He arches, craning his whole body into you. You nearly have to let go of him to keep yourself balanced. A laugh escapes you, his eagerness infectious, "Hold on, hold on."
You don't delay him further but you need to remain careful when you remove the rod. It had gone in slightly lubricated, but now it had more viscous material clinging into it from within.
Twisting it ever so slightly, pulling it up with your sterile hand, you guide it out of him. You are not teasing him, you're only exercising abundant caution as to not puncture or tear him, but he whines out again.
"Please..!"