[Jake T Catt]

Making characters that don't sound like you is tricky. One way is to model different characters on people that you know.

Or practice making up characters who are very different from each other. Try to get inside their heads. Even if your story is short, and one of the characters is just consistently mean, maybe they have a good reason for their behavior. They're secretly jealous, or something is bothering them that no one else knows about.

One exercise you could do would be to try to write about the meanest character you can possible think of. Just be sure to to dial it down a little if you end up using this guy in your writing. One note characters aren't very believable.