Same writer. Even though Black Out is based on a book, you can see similarities in the writing styles through the adaptation. Black Out also has a similar setting for the main character where he is seen as an outcast and is despised by the rest of his village community. Lots of injustice like Save Me 2 to the point it will infuriate you even more with how despicable most of these characters are in their actions.

Both shows are action heavy with corporate and governmental corruption. There is also a lot of similarity between the characters of Woo Chaewon in Blood Free and the main character of The Veil, Han Ji Hyuk. Both have similar jobs, as one is a bodyguard and the other is an agent, and their demeanor and cadence are near identical.