One characteristic is their tough and cynical nature. They've seen a lot of the seedy side of life and it has made them jaded. For example, Sam Spade in 'The Maltese Falcon' is a classic hardboiled detective. He doesn't trust easily and is always on guard. Another characteristic is their independence. They often work alone, not relying much on the police or other institutions. They have their own set of rules and ethics which might not always align with the law. Also, they are highly intelligent and observant. They can pick up on small details that others might miss, which is crucial in solving the complex cases they are often faced with.
Hardboiled detectives are typically street - smart. They know the ins and outs of the city they operate in, the underworld, and the criminal elements. They are masters at interrogation, using their wits and sometimes intimidation to get information. They usually have a sense of honor, though it might be a bit twisted. They might break some rules but they have a moral code deep down. For instance, Philip Marlowe is known for his integrity in a corrupt world. And they are often loners, with a past that haunts them, which adds to their brooding and complex personalities.
Well, they're often world - weary. They've been through a lot in their lives and in their detective work, which gives them a certain hardness. Their appearance is usually not too flashy but practical, like a worn - out trench coat and a fedora. They are quick thinkers, able to adapt to new situations fast. In a fight, they can hold their own, whether it's a physical brawl or a mental battle of wits. And they have a strong sense of justice, even if it means going against the system sometimes to get the real bad guys.