1. Ensure that no matter their backstory, they have one main character trait. This can be, for example, their relentless determination, sassy attitude, or are quick to anger. Think of toddlers, essentially. Even toddlers have a personality about them that is so integral to their being that years later they still carry that trait with them.

2. Adding ✨trauma✨ (aka their backstory, sad or not) to your character should feel like stacking bricks atop the foundation you already created using the step above. Doesn't really matter whether you come up with the character's backstory before or after introducing them. As long as it's able to describe how said character went from slobbery little toddler to how they are now, you're set.

3. Actually study how real people react to things, please. So many people are varied when it comes to reacting to the same thing. Imagine a bunny hopping out of a bush suddenly. One person might scream and jump away. Another person might try to kill it before even knowing what IT is, and another might just stand there stiffly/unfazed. You can also apply this to things like traumatic events. Not everyone is just going to mope around and beat themselves up about it.

. . .

4. Again, special tip for my fanfic writers out there, please oh please oh please oh PLEASE at least read the character's Wiki ONCE before writing them into your story. (I read their wiki pages occasionally throughout the writing process to try to make sure I am sticking with canon best I can. Yes, even if they have undergone a great deal of character development outside of canon.) 🙏 Instead of just using them like dolls to act out scenarios literally any other cardboard cutout could do, perhaps instead consider how that character's unique traits can be used creatively to enhance the story, nay, even to help create the a kind of story only THAT character could. If you feel like you're having to completely change the characters to fit into your fanfic, then honey, that's not a fanfic. That's just you playing God inside someone else's sandbox.