What makes a really good adversary in a crime story?

[Ben]

You can probably identify a bunch of 'typical' baddies that populate the world of crime fiction, such as the jilted lover, the mafia boss, the mad genius etc. But what, for you, are the characteristics that make up the best adversary for our protagonist?

[Zoe]

Someone that is both sympathetic and not moral and yet normal that too me is a great adversary

[shanghao]

Someone who definitely has to be deviously clever. But on the other hand, is still humane and has his/her own moral standards, albeit a twisted one. They can appear to be cold blooded or diabolical, these being masks that they wear to simply survive.

And it'd be even greater if this character repents in the end and receives some sort of redemption.

[Annette]

Someone with a mysterious past that is, in part, responsible for their actions. A well-developed character that allows us to see their point of view, albeit twisted. If an author wants to either continue a series or be true to the definition of a psychopath then the villain
Cannot repent (wouldn't seem believable to me).

[Zoe]

I agree ^^ to me an adversary has to be almost normal as in someone you would never glance at a second time and yet has something about him that is not right but can be charming and humourous

[David]

I like the adversary to be the near equal of the protagonist in skill and smarts.

The adversary (especially the serial killer) who constantly out-performs the main character for 90% of the book - until he does something colossally dumb that gives him away or the main character has a blinding epiphany that reveals all - is unrealistic.

[Amber]

The best adversary is different for each protagonist. What is most challenging or threatening to one character will not be for another. It also depends on the subgenre and mood of the book. If the antagonist brings out the protagonist's weaknesses as well as strengths, it brings an added dimension to the character arc.

[David]

The best villain I know is Merrick in The Raj Quartet. (People don't ordinarily think of these novels as crime stories, but why not? They're about rape, murder, police corruption and an innocent man wrongly jailed.) He does very bad things, but in many ways he's a good, even admirable man: smart, dutiful, courageous. It's not entirely his fault that he suffers a lot, and he bears it stoically. He gives me the creeps, but I sympathize with him.

[Amber]

David wrote: "The best villain I know is Merrick in The Raj Quartet. (People don't ordinarily think of these novels as crime stories, but why not? They're about rape, murder, police corruption and ..."

Good illustration. I read those books years ago, but you brought his character back to me vividly.

[Ben]

Amber wrote: "The best adversary is different for each protagonist. What is most challenging or threatening to one character will not be for another. It also depends on the subgenre and mood of the book. If the ..."

That's great point about the antagonist bringing out the protagonist's weaknesses, as well as their strengths.

[Ben]

David wrote: "The best villain I know is Merrick in The Raj Quartet. (People don't ordinarily think of these novels as crime stories, but why not? They're about rape, murder, police corruption and ..."

Not yet read those, but you've got me so intrigued that I'm off to take a look now!