Fallen Stars

The devil doesn't come dressed in a red cape and pointy horns. He comes in everything you've ever wished for//
As an experiment, the angels send one of their own to study and report human life in today's modern society. Only a few are willing but only one can be sent down; his name is Markus. Looking for a chance to prove himself, Markus goes to Earth and lives in his life as a human for a few weeks, reporting back to Heaven every three days.
However, on the eve of his return home, Markus gets an unexpected visit by Heaven's worst enemies and is marked by a powerful demon, preventing him from returning to his home. Devastated and longing to return to his home in the clouds, Markus is held hostage by said demon and without a plan to escape his bonds, Markus must now live out eternity trapped on Earth with no way of getting home.
So what's an angel to do?