Protagonists have to be emotional beings. Without being clued in to their Interiority–thoughts, feelings, reactions to what’s going on in the world–and without getting a sense for their emotional lives through voice and the way that they describe everything and everyone in your story (this applies to third person, too), we won’t truly know them.
As a writer, it’s your job to clue the reader into emotions at every turn, but always through Interiority and showing. Telling when it comes to characterization and emotion is probably one of the biggest problems I encounter in manuscripts.
But even when you manage to convey emotion correctly in your novel or picture book, don’t be content to play on the surface. In a good book, there should never be just “happy” or “sad.” All emotions have causes, degrees, and consequences. The more complex the emotion in every situation, the more specific you’re being, and the more engaged your reader will become.
For example, prom is something a lot of teens look forward to. But “happy and excited” can also be cliché and boring. Not to mention unrealistic. A much more authentic experience for your character might be that prom is actually bittersweet. Sure, it’s the event of the year, but it’s also a rite of passage for graduating seniors. It’s a signal that the year is almost over and that this is one of the last times all these friends and enemies and peers and teammates will be under the same room ever again. For every emotion, find it’s shadow or highlight, search for a deeper layer, and give your reader several facets.
You can easily do it in Interiority. If we run with our prom idea, planting seeds of melancholy can be accomplished quickly and efficiently like this:
“Cheese!” Lacey grinned at the camera, clutching her date. As the flash went off, she felt a pang of nostalgia sharp enough to make her draw a quick breath. This will all be over so soon, she thought. But then the thumping bass beckoned her from the hotel ballroom, and she marched off toward it, ready to be lost in a crowd of her friends.
Ideally, we’ll get the primary emotion–excitement–and then hints of something else. No matter how you accomplish it, this kind of layered narrative is always infinitely more interesting to me as a reader, and it makes for much richer character.