Making Your Characters Real Individuals, Making Them Stand Out

A MG (middle-grade fiction) writer in one of my past online classes posted a great question that sums up the main struggle most of us have with writing vivid characters.

How do I make my characters more distinctly individual? Different from each other, realistic enough to be believable, clearly so on the page?

Developed characters, fictional or real, should be individuals: distinct from others in the story. If they all blur together, it's hard to make them come alive for the reader.

One key to writing clearly individual characters is their backstory, the history that informs their story decisions. That's internal research that's often fun (and challenging!) to do.