How can one create a believable character in 'Star Wars Darth Vader self - insert fanfiction'?

To create a believable character, think about their motivation. If you're in a world with Darth Vader, your character might be motivated by a desire to gain Vader's approval and rise in the Sith ranks. Also, consider their personality. Are they more calculating like Vader or impulsive? Their interactions with other characters, especially Vader, should be based on these aspects. For example, if your character is impulsive, they might often act without thinking, which could either annoy or amuse Vader, depending on the situation.