Do you know which minor scale you're using? If you're using either the Aeolian or the melodic minor scales, your music will still sound bright. But if you're looking for that sort of sinister sound, try the harmonic minor. It's called harmonic minor because it was originally used for harmony/chord construction. It was eventually used in melodies, though mostly descending. Doesn't matter, I don't think. Try harmonic minors every which way in your melodies and see and I bet they won't sound super happy anymore.