Ava's Demon, Book 1: Reborn (comics)

A PACT IS MADE... When a young, shy girl named Ava discovers that the demon who haunts her is actually the spirit of an ancient alien queen named Wrathia, the two form a powerful pact-in exchange for a better life, Ava must help Wrathia seek revenge against TITAN, the god-like being who destroyed her empire. To aid Ava against TITAN, she must first assemble Wrathia's most trusted warriors and the lifeforms they haunt.

The only problem is, she doesn't know what they look like, or where to find them. Joining her on her mission is Maggie, Ava's former best friend and fellow refugee, Odin, a brooding young man with a mysterious past, and Gil, a dedicated follower of TITAN. And unbeknownst to Ava, all three of them are hiding their own inner demons...looks like Wrathia's army might be closer than she thinks.