Deadly Lineage by MJ May

Shunned by most species and abandoned by their warlock fathers, necromancers are marginalized, feared, and reclusive. Erasmus Boone is different. His warlock father chose love instead of abandonment. Unusually powerful and talented, Boone’s embraced his necromantic abilities and managed to carve out an existence within a world that would rather he not exist at all.
Humans aren’t the most respected species. Hell, they’re just a step above termites in the eyes of most. Detective Franklin O’Hare has never taken derision towards his humanity to heart. Determined to do the best given his human limitations, Detective O’Hare does whatever it takes to right the wrongs of the world—no matter the species concerned—even if that means working with a necromancer. Besides, Erasmus Boone isn’t so bad. In fact, he’s temptingly perfect.
Seeking solace after a difficult case, Boone walks the typically peaceful gravesites of Trinity’s Holy Cross Cemetery. The gentle hum of contented, long-dead souls ease Boone’s mind—until he’s hit with an unearthly cry unlike any he’s heard before. Unfortunately, that first soulful cry isn’t Boone’s last, each wail revealing a disconcerting pattern. There’s a serial killer in the wind, and their murders are resulting in souls with painful, missing pieces, leaving their voices incoherent and
indecipherable.
Boone and O’Hare must work closely together if they’re going to stop the killings. O’Hare learns quickly that keeping Boone safe from disgruntled clients and serial killers is a never-ending and nearly impossible task.
As O’Hare and Boone grow closer, so does the killer. They need to figure out who’s indiscriminately murdering seemingly unrelated species, and why the victims’ souls are devastated beyond repair, before Boone becomes another victim on the ominous list.

Deadly Lineage is the first book in the Necromancer Tales series. This series is a spin-off of the Perfect Pixie series and takes place in the same world but can be read as a stand-alone. Deadly Lineage is a M/M romantic fantasy mystery with an unusually sane necromancer just trying to make a living, a humble human detective attempting to ignore his attraction to the aforementioned necromancer, an arrogant but redeemably overprotective warlock father, a twisted serial killer, a questionably agreeable all-powerful djinn, damaged souls, humans-some redeemable and some not, a steamy Mississippi summer, and far too much sweet tea. Deadly Lineage has a HFN ending.

Mentions of violence, murder, souls bruoght back from the beyond, speciest bigotry, and a few characters of questionable morals and sanity.