Yes, usually. The idea of black spectres is often associated with the unknown and the spooky. Their shadowy forms and the mystery surrounding them make for a scary narrative.
One 'black spectres story' could be about a black spectre that haunts an old, abandoned mansion. People claim to see a shadowy figure in the hallways at night.
Well, it could be a story where an EMT encounters a really strange situation with a patient who is somehow 'unseen'. Maybe it's a case of a presence being felt but not actually seen, like some kind of spooky or unexplained phenomenon during an emergency call.
A simple Ant Man and Ghost fanfiction could be them having a friendly race through the city using their unique abilities. Ant Man shrinks down and zooms through small spaces while Ghost phases through obstacles. It would be a fun and light - hearted story.
A human peasant could also be a central character in the fanfiction. This peasant, despite having no combat skills or great power, uses his wits and knowledge of the land to help the resistance. He could be the one who discovers hidden paths or food sources that keep the good guys going during the tough times of the war.
In Mr Robot Elliot OC fanfiction, the character development of the OC can be really exciting. They could be from a different background, such as a corporate insider who turns against their own company. This OC could bring a fresh perspective to Elliot's world. Maybe they have a special skill in decrypting codes that even Elliot is impressed by, and together they take on the powerful E Corp in a whole new way.