This is a series that came to me in a dream. Okay, partly in a dream the other part was from the song of the same name by Bring Me The Horizon.
This world is basically fey and demons living among the human population without them knowing the humans know the others exist.
Book 1: Blessed With A Curse... is where we learn what Experimentals are... or more to the point who they are.
Fey like things to be perfect and anything not deemed perfect is cast aside... enter the experimentals... the ones their own kind didn't want yet some decided it was okay to take the defects and use them for their own gains.
In this first book Storm and Heath discover what's happening and decide to put a stop to it as they fight to find a cure for what's wrong with Heath, but will years of hurt and misunderstanding be enough to save their love as well as their lives.
Book 2: Running Into Zero Tolerance... Linc has found his mate in the most unlikeliest of places and is now on the run with Skylar as they make their way to the safety Storm and his band of misfits are offering. Along the way they have to face untold enemies as well as picking up a few strays who also need saving.