What are some effective ways to reveal your protagonist's motivation?

One note that I would add to this is that it’s important (apart from certain specific circumstances) to not have your characters outright state their motivations. Instead, try to make them clear through subtext, what is not said, or by making it clear that they’re not being truthful.

Dialogue is a powerful tool to convey a protagonist's personality, motivations, and values; however, just as in real life, it is not the end-all and be-all method. This brings to mind the old storytelling maxim: "Show, don't tell." Think about everyday life. Certainly, talking with other people helps clarify one's motivations / personality / values. However, our actions, certain context, implications—or, simply, what goes unsaid—are all also powerful in revealing our truths. When using dialogue, it's important to use it to further the story and your characters' journeys, and not as a crutch.

One of the biggest mistakes I see with dialogue is forgetting to add action items within the text to break it up. Body language is 80% of communication, so we should be reading about it during a conversation between your characters!

I think there ARE fine examples in literature of characters explicitly stating their motivations. This is particularly effective for nefarious characters as a way of bridging understanding for the audience. After all, we are educated readers -- not coldhearted murderers. Case in point, in the very beginning of Richard III, Shakespeare has Duke of Gloucester, soon-to-be-King Richard, declare: "I am determined to prove a villain / And hate the idle pleasures of these days." That's in the wonderful speech that opens the play with the famous lines: Now is the winter of our discontent / Made glorious summer by this sun of York / And all the clouds that lour'd upon our house / In the deep bosom of the ocean buried.

Other actions that reveal motivation include body language descriptions. "He walked away with his head hung low and feet shuffling as if they weighed twice as much." Body language speaks louder than words anyway, so why not tap into the body language of your protagonist to demonstrate motivation?

One mistake I see new writers make is to explain the action taken. "She nodded to show she understood." Or, "I walked her to the door because it was dark." Keep two things in mind when writing action: 1. Your readers are clever - you don't need to explain everything to them. 2. Half the fun of reading is the detective work of figuring out why the characters do and say the things they do and say! Don't tell us why they did something. Show it through setting, actions, and dialogue.

The art of subtext can capture the essence of subconscious thoughts and emotions. It can be the liminal space between a range of ideas, leaving expansive room for the readers subjective interpretation of the protagonist's history and motivations.

Use interiority to show an internal struggle/debate between to equally bad or equally great choices. Let the reader see how your protagonist cones to their decision. Instead if, "Although she knew she'd lose her best friend, she agreed to the deal." Try, "Afia will hate me if I take this deal, but what else can I do! Rent is due tomorrow."

Revealing your character's motivations is made more potent when it lines up with or intriguingly contradicts how you've characterized them. For example, a protagonist seen to be the 'strong and silent' type might reveal their motivations through their actions or internal forces. Or—if this choice fits your narrative direction—they can externalize it themselves, seemingly flying in the face of how they've been characterized to that point. Whatever you choose, know that your characters are humans, and so are complex; you can almost always justify your choices when they're authentic to the character.

Psychosynthesis is a framework that offers a wonderful marriage of both internal and external forces in the gradual evolution of a protagonist's character.

It’s perfectly valid to have your audience or reader do the work. Providing them with hints from various sources within the story and allowing them to discover your protagonist’s motivation before it is clearly revealed can create a great sense of catharsis in your writing.

In my current graphic novel, BROKEN 💔 by Dwight Thompson, I'm actually using the secondary character to reveal the main character's motivation. Think Lost In Space more and less Robinson Crusoe. - TWW