Inhuman by Mar Qaroll

[Human Shed Skin Book One] During a response to a demonic attack, inhuman hunter Jean-Luc Lowell nearly loses his life, only to be saved by a tentacle emerging from his best friend and lover, Celezar.

While dealing with this revelation, he learns the demon attack was the first of many caused by creatures far more powerful than anything humankind has dealt with in millennia.

With Celezar stubbornly remaining by his side, Jean will relearn the definition of "monster" while dealing with the new threat.