Vampires (A multiple ship fanfic)

Nightmare and Geno are two doctors that have been sent by King Asgore to help a small, remote town that is necessary to help build trade centers.

Later they are joined by Lust and Dream, two merchants that are sent by the King to also assist the town. Ink, a famous artist, follows his friends to the town as well.

Once they arrive at the town, they are greeted by two guards: Cross and Blue who have been assigned as body guards to the group.

They are warned by the two guards repeatedly to not go into the forest that surrounds the small town. But, why? Why not go into the forest?