Rogue Demons, Wicked Fate by Alexa Gregory

Life shouldn’t be able to sneak up on a psychic witch, but when it does? Zéryphine Dread is led straight to Hell where she finds a noble demon, a reluctant fighter, and a royal coup.
Zéryphine’s life is predictable. At least, it used to be. The last thing she expected was for her sister to pop out of a portal, insisting that Zéryphine enter Hell to help protect the royal family from a dangerous uprising.
Torren and Caspiel are two very different demons. One is a fighter in the Pits of Hell, and the other is a noble. Their relationship is threatened when Caspiel gives away some of his powers to help Torren escape the Pits. Hiding from their enemies, their only protection is a deep connection with Zéryphine. The enthralling psychic claims she needs their help.
Locked together in a mission to save the royal family, the two demons and the witch will have to fight to find the truth behind the prophecy before it’s too late.