astrodickology:

Capricorns aren’t a sign normally associated with darkness..but Capricorns are usually very dark. With Saturn as its ruler, many Capricorns are well acquainted with pessimism and sorrows. Many Capricorns have dark humor and are associated or drawn to the darker things in life. Like Scorpios they know how dark and depressing life can get, so many use humor as a cover up. The difference is, while Scorpios usually come around to embracing the darkness within themselves and in the world, many Capricorns tend to bury theirs deep within themselves.