"He's not an evil man, unfortunately ... That makes him all the more harmful. If he as evil, we'd kill him. No, he's ... chaotic."
Ben Spenser has come to London for one purpose: to track down Jonah Pastern, windwalker and thief, and punch him in the face. Ben loved Jonah, and Jonah betrayed him and wrecked his life. Ben's career in the police force is over, his parents have disowned him, his landlord evicted him, he's done ten weeks' hard labour for gross indecency. He has nothing left except the desire for vengeance.
Except, of course, that it's never that simple. And Jonah Pastern, once caught and roundly punched (after which he saves Ben from a police raid), claims that he loved Ben too, and wants to explain his poor life choices. Ben is determined not to be fooled again, but then he discovers that at least some of Jonah's crimes were perpetrated in order to protect Ben himself. Maybe it was all lies, but Ben can't help wondering if Jonah -- illiterate Jonah, whose first instinct when trouble looms is to run -- might be worth saving from police forces magical and ordinary, and even from himself.
Another good, thoughtful fantasy with M/M romance from KJ Charles, who writes about poverty, destitution and gaol and about windwalking (levitation), fluence (mind control) and how to have a conscience. Jackdaw (which is set during and after The Magpie Lord) is a good read, though somehow darker -- and more focussed on the protagonists' relationship -- than others in the series.