Feathers of Darkness Duet by Sadie Winchester:
 
This books both books in the Feathers of Darkness Duet: Sleeping Redemption and Redemption's Awakening

Despite the wings on my back, I fell from grace into Lucifer’s reign. Wickedness consumed me, and the demons of my past drove me mad.

So far from redemption, the stars wept for my existence. Not even an unhinged trickster demon, my inept guardian angel, and an archangel with a permanent scowl could save me from my biggest enemy—myself.

After thinking the Abyss could put my soul to rest, the scales shifted, and I was awakened.

With renewed bonds between the three pieces of my heart, I’ve come back to finish a war started by a demon who seeks to destroy everything.

These feathers of darkness in my wings remind me that redemption comes at a cost. But nothing will stand between me and my three saviors ever again.

This book is intended for mature audiences 18+ years old. Please refer to the author's website for all content warnings.