Kylo's final training apparently included some heavy body modification and a whole lot of weird Sith magic - now he actually has reasons to hide beneath his armour, though even then it's obvious he's changed, become larger and stranger.

When he's sent back to the Finalizer he avoids Hux, fearing the inevitable rejection and disgust.

Let me throw too many suggestions at you
- Kylo's definitely inhuman now - muscles thicker and limbs longer, fingers ending in claws, bony protrusions along his spine, mouth splitting his cheeks and filled with fangs and an obscenely long tongue, body partially covered in scales and strange sigils, black bodily fluids, etc
- weird cock - much bigger and downright freaky (ridged/has a knot/prehensile/???), sitting over massively bulging testicles (maybe a cunt too?)
- cybernetics reinforcing and replacing parts of him
- if Hux is disgusted by all this it's only at first

If there's sex I'm not picky about who tops. And I'm down for pretty much any kinks except scat.