No creative adventure is complete without good characterization and if you don't know your characters, the audience won't either! Here's three fun activities to do that will help you develop your characters.
Reaction Charts
Charts
Think about those memes that show each character and what they'd say in a situation. Even those one lines say a lot about each personality. Try it with your character's too! It can be a situation from the plot or something silly. I suggest combining a summary of how they would react with a line of inner thought and a line they would speak out loud. Knowing how they would respond in a pinch will be useful in your work but so will knowing the difference between what they'll say in the privacy of their own mind compared to what they'll say out loud.
Astrology
Astrology
https://www.everypixel.com/search?q=horoscopes&stocks_type=free&image_id=17413490283641411452
Try deciding which sign your character is. If they have to have a certain birth date for a plot reason, you don't have to stick to their official sign but can into which sign you think they're the most like. Write a list out of typical traits for that sign including negative and positive aspects. Also look into what their rising sign would be. Try pairing different characters together. Do they get along? In what ways are they compatible? Would they fight a lot? Would they have passive fights or physical ones? It's a bit overwhelming to think of character interactions from scratch so horoscopes are a great base.
Journals
Journaling
https://www.everypixel.com/search?q=journal&stocks_type=free&image_id=17681648735728319875
Scrapbooking and journaling are not only great stress-relievers and ways to exercise your artsy muscles but can also help you develop your characters. There's many ways you can approach this: scrapbook objects, such as from nature or using print outs, that fit your character's likes or mood, free journal about them as if writing a diary entry (or make the diary entry from the character's perspective), or create a profile as if the character was making a Facebook or joining a dating website. If you feel comfortable drawing, even try making a portrait of your character to add to the page. If you like to re-use character shells for other works, it's great to have a notebook of your characters so you can go back through them. Consider adding their reaction chart and horoscopes to their page, as well.
It's especially useful to get your character's essence out on paper where you can reference it throughout your work and when you return for revision. You can always take any of these ideas a step further by examining how character's would interact across multiple works you may have or in different time periods or settings. Have fun getting to know your characters!
