Multidimensional Characters

To craft a multidimensional character utilize a mix of simplicity and undertones of realism. If you use a character as a tired cliché they will come off as a heavy handed caricature rather than a person. Beyond character identifiers, physical appearance and quirks that define someone it is the flaws that make an unsettling 'perfect' image look real. 

Relatable or morbid fascination. Think about characters that you have connected to often times it is because there is something personally relatable about them. Exposing a weakness not only humanizes a character, but allows them to be relatable. If a character is not relatable but still a main character it is often due to morbid fascination like with serial killers.

Needs, wants, and values. This is probably the most important part of this article. Knowing the answers to these three questions will help know your characters. Needs are things that your character needs such as what is central to the survival of your character. Wants are things that they yearn for like love. Values are a guiding code of ethics (or lack thereof) or what they hold dear in beliefs. Values guide their reactions to their motives of needs and wants.

Know your characters psychology. With every action ask 'what is their motivation' as if you were a detective trying to solve a homicide. 

You can exploit and subvert stereotypes and expectations. When working with stereotypes just remember no one fits in a box. Be careful what you paint, it can have a lasting effect.

Not everyone acts the same way in the same situation presented to them in the same way. There are ethical questions that arise when you base characters off of real people. If you don't create them from scratch mix other qualities and the person up enough that the result would be unrecognizable. Either way, I recommend steering away from that unless you are writing a memoire or biography.