To capture a butterfly

Isaac Blackwoods has spent his entire life running from shadows. From the mansion where his father's voice was a weapon, from the nightmares that follow him into every restless sleep, from the chains of a past he refuses to name. At twenty-two, he finally has a chance to carve out a life of his own-a rookie detective with a brilliant mind and a heart too soft for the cruel city he serves.

But angels never walk unnoticed. And Isaac? Isaac has caught the eyes of monsters.

They don't fall in love. They consume. They don't chase. They claim.

And now their eyes are on him.

To them, Isaac is not a detective. He is not a rival. He is theirs.

Their butterfly. Their obsession.

Isaac believes in justice, in peace, in the quiet discipline of a life not ruled by violence.
They believe in blood, in power, in keeping what belongs to them no matter the cost.

He thinks they're his enemies.
They think he's their future.

And when angels and devils meet, only one truth remains: obsession is the most dangerous game of all.

Tropes:

Detective x criminals
Evil x angel
Obsession
Possession
Mafia