Having a compelling character is not just that of a character with a likeable set of traits. It is also beyond just the little trivial details.
To me, what makes them compelling is often something far simper than that. It is putting them into a difficult position and then forcing them to make a choice.
And understanding just what is the choice they would make and the reasoning behind why. And here to me, is also some of the ways I make them compelling.
#1 What matters to them?
It is really much better than trying to list out their favourite food, which seems nice to know but what purpose does it serve to the story. You can list out every single thing and still not make them care without answering this question.
This question puts is asking what would get them to pull out all the stops so they don’t lose it. Or take it away from them to see what they would become. And how they would grow without it. Or what would they do to protect it.
This can mean the lengths they would go, or the importance of it in their lives. That once removed, it would make them go to a grinding halt to realize that it’s gone and they need to cope without it. Or try drastic means to get it back or still maintain it.
#2 How do they solve the problem?
This is the question everyone should ask themselves. How would they come up with a solution which is something that is in line with their reasoning but also resolves the main plot entirely.
Or rather not exactly that but they’re willing to settle at it, or that is the best they got. Not everything can work out perfectly, and an imperfect plan, or a gamble is a great way to get them to understand. Especially if the alternative is heart wrenching for them.
Such a question would also give you insight into the sort of character they are. What is their personality, their worldview, their values.
#3 How far will they go?
Apart from the question of what matters to them. Another important is the methods would they turn to achieve their ends. Is it ethical, kind, or ruthless. Unrelenting, quiet or shouting it to anyone at the top of their lungs.
Showing the lengths they would go to achieve something is also a very good indicator of the sort of personality they have. And can also hint at growth, or things that the main character needs to learn or their specific flaws. Everyone can have thoughts, good ones, bad ones, but most of them would never be turned into action.
And draw understanding to them and who they are. Or where they need to grow, and by the end of the book, just what have they learned and what is their growth.