Daemons, Inc. Series by Camille Bacon-Smith

Marnie had no way of knowing that Kevin Bradley and his partners were not the mere mortals they appeared to be. And they were, indeed, the only "people" who stood a chance of rescuing her brother from his equally inhuman captors--captors to whom Paul was the merest of pawns in their multidimensional, millennia-spanning campaign of conquest.

Bradley, Ryan, and Davis, Private Investigators was the most unique detective agency in Philadelphia, because Kevin Bradley and his partners, Evan and Lily, were not the mere mortals they appeared to be. Brad and Lily were powerful demons, and Evan was Brad's half-demon/half-mortal son. Solving earthly crimes ought to have been a cinch for them... moreBradley, Ryan, and Davis, Private Investigators was the most unique detective agency in Philadelphia, because Kevin Bradley and his partners, Evan and Lily, were not the mere mortals they appeared to be. Brad and Lily were powerful demons, and Evan was Brad's half-demon/half-mortal son. Solving earthly crimes ought to have been a cinch for them. But when someone began stealing the crystal balls which had belonged to the centuries-dead Dowager Empress of China, Brad and Evan found themselves hard-pressed to track the criminal mastermind down. For the thief was a dangerous -- perhaps unstoppable -- adversary...even for those with powers beyond anything known in the mortal realms. less

The paranormal mystery of Eye Of The Daemon and Eyes Of The Empress together for the first time!Kevin Bradley and his partners are uniquely qualified to handle cases involving the occult. He and Evan Davis are far more than the mere mortals they appear to be. Kevin is a powerful daemon lord, and Evan is his half-daemon, half-human son. Solving mortal crimes should be a cinch for them. But somehow, they never get the easy open-and-shut cases.

Third in the paranormal detective series Evan Davis and his partners, Brad and Lily, attract the jobs no other detective can handle-cases with a dangerous, otherworldly slant. But no one is better equipped for this because Lily and Brad are powerful daemon lords, and Evan is Brad's half-daemon son. Now, however, the trio face a real challenge---involving armies of daemons, and wealthy mortals who have delved far too deeply into the dark arts...