I'm not entirely sure as I haven't read this specific story in detail. But generally, it might be about some secrets hidden within the 'Silent Earth' and perhaps the adventures or revelations related to those secrets.
There are a few graphic novels that come to mind. 'Preacher' has a dark and edgy feel to it, with complex characters and a twisting plot, which is similar to what you might find in 'In Keeping Secrets of Silent Earth 3 Graphic Novel'. 'Transmetropolitan' is also in the same vein. It's set in a strange and futuristic world and has a lot of depth in its storytelling. Additionally, 'Hellboy' has that same sense of mystery and action that might appeal to fans of 'In Keeping Secrets of Silent Earth 3'.
Well, without having read the entire novel in detail, it could be things like hidden magic, undisclosed relationships among the characters, or perhaps long - forgotten histories within the story's world.
One keeping secrets story could be about a child who found a box in the attic. Inside were old letters from a relative's past love. The child kept it a secret as they felt it was a precious discovery that the relative might not want to be public. They hid the box again, and that secret stayed with them for years.
A 'keeping secrets novel' often features a build - up of tension. As the story progresses, the secret seems to be on the verge of being revealed but is held back. The protagonist is usually in the middle of this web of secrecy. Maybe they accidentally stumble upon the secret or are entrusted with it. There are also often side characters who are either trying to uncover the secret or are unknowingly helping to keep it. The pacing is important too, slow enough to build the mystery but not so slow that the reader loses interest.
By constantly teasing the secret. Drop little hints throughout the story that make the reader curious. For instance, if the secret is about a hidden treasure, mention strange maps or old legends related to it.
One way to keep secrets in Dragon Age fanfiction is through the use of misdirection. For example, have a character seem to be hiding one thing when in fact they are hiding something else entirely. Another approach is to limit the POV characters' knowledge. If the story is told from a single character's perspective who doesn't know the secret, the reader will be in the dark as well until the right moment for the reveal.