Into The Darkness (Books 1-6). Eternally Mated, #7

Fall Into Darkness:Eli has faced his share of enemies, many of whom were once his own brethren. But when the ruling body of the Seven learn a human dies on his watch, they question his compassion. It doesn't take long for the angel to find himself wingless and back in the mortal realm. He's never been a saint; a bounty hunter always holds a darker side. But his clock is now ticking and if he doesn't learn empathy soon, the next place he will land is directly in Hell.
Veiled In Darkness:'Death' is not a nickname Ashley wants but it is who she has become. Her mating with Eli brought about her change and no one expected the Angel of Death. Now, she is the only one who can stop Lucifer and his evil plan. There is just one small thing, she must embrace who she is and doing so may darken her forever. Bound By Darkness:An angel warrior is never supposed to disobey a command but that is exactly what Lyzander did.
Twenty years ago, he spared a little girl's life while his brethren murdered her family. Now he finds himself a captive in the worst place an angel can be. The pits of Hell. No one is coming to save him until a mysterious female shows up wanting to make a deal. Unleash The Darkness:Being a reaper means Sephtis is bound to both Heaven and Hell. When he is called upon to escort the damned, he unleashes a power even demons fear.
It's only his mate, Evangeline that keeps him from embracing his darkness and he will do anything to keep her safe. Surrender To Darkness:Cade is a fallen angel who endeavors to follow the right path. That is until the angels' ruling body decide the warrior is the perfect match to carry out their new assignment. Schooling the young, snobbish Abagail in the art of demon fighting is a challenge he could do without.
The female tests him at every turn yet tempts him to show just how bad he can really be. Tempted By Darkness:Tegan is an elite archangel so; commanding armies and ordering deaths is everyday business to him. When he's handed a mission to gather intel on an emerging species, he finds his beautiful young partner a challenge he's not sure he can handle. She stirs desires he has avoided for decades, and it forces him to confront a past he thought he had left behind.