Cap moon here! emotions are hard, and SLOWLY processed :/ Not sure if that qualifies for dark though.
The darkest person I met was a Libra sun/Scorp moon combo. & by dark, I mean emotionally complicated (Idk if that makes sense).
Scorpio - emotional darkness. Capricorn - emotionless darkness. I can deal better with the Scorpio darkness than the Cap darkness.
Although they are both well acquainted with darkness, the goat is aiming to move up to a summit.
I like these signs together. My cap+ 8th house, loves a good brood.
many of the Caps I know are often very detached from the visceral, practical-minded...
Scorpio of course is the opposite
I love both Capricorns and Scorpios. I think both are dark, but different dark. I find Capricorn's darkness more difficult to penetrate than Scorpio's. Energetically, I can deal better with Scorpio's darkness than Capricorn's. It could be my Scorpio Saturn...