One way to remove fingerprints from comic books is to use a mild cleaner specifically designed for delicate surfaces. Spray a small amount on a cloth and then gently rub the affected area. Make sure to test it on a small, inconspicuous part first to ensure it doesn't cause any damage.
In movies and novels, it was common for the ancients to press their fingerprints on promissory notes or confessions to confirm them, but it was not a unique technique of the ancients. In fact, in ancient society, people generally lacked the technology to identify handprints in the modern sense, but the confirmation of handprints still had its importance on the legal and moral level.
In ancient China, the verification of fingerprints was usually achieved by stamping or signing. In law and letters, seals were often used to confirm the authenticity and validity of documents. On the moral level, people would use signatures or handprints to show their sincerity and commitment.
Although the ancients lacked the modern technology to identify handprints, they still used other methods to confirm the authenticity of handprints. For example, in ancient China, people would leave their handprints on bamboo slips to prove their promises and identity.
Although the plots in movies and novels were fictional, there were indeed some similar practices in ancient society. The confirmation of mudras still had its importance on the legal and moral level.
Perhaps the bloody fingerprints are a sign of a dark ritual. In the Twilight fanfic, it could be that a group of vampires or some other supernatural beings are performing a ritual that requires blood. The fingerprints are left accidentally during the process. And this ritual has the potential to disrupt the balance between vampires, werewolves, and humans in Forks, so the main characters have to stop it.
Edward could also be the main character. He has his vampire senses which could help him analyze the bloody fingerprints in ways humans can't. He might be on a mission to protect Bella and the rest of his family from whatever danger the fingerprints signify. Maybe he suspects that it's a new threat from a nomadic vampire group and he has to use his skills to track them down.