You are the Sulking Prankster
A lonely spitekeeper who calls it justice and gets even alone.
What kind of villain
Your 'evil' springs from feeling wronged. You take no one's side, convince yourself 'this is just payback,' and get even all on your own. But your target is always the exact person who slighted you — a grand vendetta against the world is far too big for you. Soothing your sense of justice with impulsive, modest spite, you're less frightening than an endearing, slightly pitiable rascal.
In everyday life
When something unfair happens to you, you don't easily tell anyone. Asking for sympathy is something your pride won't quite allow. Instead you reach a verdict privately and quietly begin to keep your distance. From then on their requests are all declined — politely, but firmly. They may freeze without ever knowing why, while inside you the quiet trial and sentencing are already complete.
Similar characters
the Home Alone burglars, Tom from Tom & Jerry.
Advice
The strength to judge for yourself and protect your own heart is a solid independence not everyone has. But when you are the judge, the prosecutor and the jury all at once, a verdict can tilt one way without you meaning it to — and the other person may never have had a chance to clear up the misunderstanding. Before you hand down a private sentence, try opening up to just one person you trust: "Do you think I'm being too sensitive about this?" That one warm question will rescue you from hollow loneliness more times than you'd expect.